This is lever five of five. If you've followed the series, you've worked through Traffic, Content, Conversion rate and Average order value. Retention is the one that closes the loop.
It's written for you and your team at an established brand, typically somewhere between £1m and £3m, ready for the next stage of growth. You already have customers, orders and years of data. The job now is to optimise what you already do, with smarter use of data, technology and the human touch.
Retention is where the profit lives
The first order often barely covers what you paid to win the customer. The second order is where the business starts to make money. Every order after that is profit you didn't have to buy again.
That's what makes retention the lever that keeps growth sustainable. A brand that builds for repeat purchase needs less ad spend every year to stand still. A brand that doesn't has to keep buying the same growth, at an ever-rising price.
And it's built from your own data. Your customers have already told you when they come back, what they come back for, and why they bought in the first place. Most brands just haven't asked the right questions or joined the answers up.
A quick illustration. Take a £1m brand: 1,000,000 visitors a year, a 2% conversion rate, a £50 average order. That's 20,000 orders. Say 15,000 of those come from first-time customers. Get five more in every hundred of them back for a second order and that's 750 extra orders, or around £37,500, without a single extra visitor. The numbers are illustrative. The principle holds at any size.
Signs retention is holding you back
You don't know what share of customers buy a second time, or how long it takes them.
Your post-purchase emails go out on a schedule nobody can explain.
Your welcome emails are mostly a discount code.
You've never A/B tested a Klaviyo flow, only campaigns.
You run a post-purchase survey, but nobody does anything with the answers.
There's no automated email to win back customers who've gone quiet.
Ad spend keeps rising just to keep revenue where it is.
You sell something people use up, but there's no way to subscribe.
Every customer gets the same emails, whatever they bought and why.
How to find the leak
Each question below has an answer sitting in a tool you probably already pay for.
What share of customers buy a second time? Lifetimely's repeat purchase rate.
How long do customers usually take to come back? Lifetimely's time between orders. This is your real repurchase window.
Which first purchases create the most loyal customers? Lifetimely cohorts, broken down by first product.
Which channels bring customers who come back? Lifetimely cohorts, broken down by acquisition channel.
Why did customers buy in the first place? Fairing's post-purchase survey answers.
Do my emails land before customers drift away? Klaviyo flow reports, set against the time between orders.
Which products get bought again and again? Your order history. Look for products reordered at regular intervals.
How to optimise it
Know your two numbers. Your repeat purchase rate, and the typical gap before a second order. Everything else hangs off these.
Split repeat rate by first product and by channel. Some first purchases lead to a second far more often. Some channels bring buyers who never return. Put the loyal first products in your ads and on your homepage. Shift budget towards the channels whose customers come back. Review both splits monthly, so you spot a shift while you can still act on it.
Time your post-purchase flow to the real repurchase window. If customers typically reorder at 38 days, your reminder needs to land around day 30. Build the flow backwards from that number. A product that lasts six weeks and one that lasts six months need different flows, so split by product where the windows differ.
Make every email useful. How to use it, how to care for it, what to try next. Build the content from what customers told you about why they bought. Save the discount for later in the sequence, if you use one at all.
A/B test your flows, one variable at a time. Klaviyo lets you split test inside a flow. Most brands only ever test campaigns. Start with these:
Timing. Day 25 against day 32 for the replenishment reminder.
Subject lines. A practical line ("How to get the most from your…") against a personal one.
Content. A how-to email against a "what to try next" email.
Offer against no offer. A small incentive against none at all. You may find the offer only pulls orders forward that would have come anyway.
Judge every test on second orders placed. Open and click rates can flatter a version that never sells. Give each test long enough to cover a full repurchase window before you call it.
Ask post-purchase survey questions you'll act on. Before you add a question, write down the decision it will inform. If you can't name one, drop it. Three that earn their place:
Why did you buy today? This feeds your product page copy and your ad angles.
What nearly stopped you? This tells you which objections to answer on the product page and in your first email.
What will you use it for? This tells you which follow-up content each customer should get.
Keep it short. Two or three questions, one tap each, with an "other" box for the answers you didn't expect.
Make the answers matter. Sync Fairing responses into Klaviyo so each answer is saved to the customer's profile. Then branch your post-purchase flow on them. A gift buyer gets a different second email from someone who bought for themselves. Every few months, pull the answers together and feed them into your product page copy and your ad targeting. The words customers use are usually better than the ones you'd write.
Win back the ones who drift. An automated email when a customer passes their expected reorder date, set from the repurchase window, with a second nudge if they stay quiet.
Offer a subscription where it fits. For products people use up, make the next order automatic.
Measure lifetime value by cohort. Each month's new customers should be worth more than the last. If they aren't, one of the steps above has slipped.
The tools from the toolbox
Klaviyo: email and SMS tied directly into your store. It runs your welcome, post-purchase and win-back flows, with segmentation, personalised recommendations and A/B testing inside each flow.
Juo: subscriptions, from curated boxes to replenishment plans, with personalised add-ons and incentives that keep subscribers longer.
The insight comes from the measurement layer. Lifetimely gives you repeat rate, time between orders and cohorts by first product and channel. Fairing tells you why customers bought, synced straight into Klaviyo profiles so your flows can use it. The full stack is in The Optimisation Toolbox.
Do it yourself this week
Find your repeat purchase rate and the typical number of days between a first and second order.
Pull repeat rate by first product and by acquisition channel.
List your current post-purchase emails with their timing and content, plus your survey questions if you have them.
Paste it all into Claude or ChatGPT with this prompt:
"Here is my repeat purchase rate, the typical days between first and second order, my repeat rate by first product and by acquisition channel, my current post-purchase emails with their timing, and my post-purchase survey questions. Tell me where my emails land too late, which first products and channels I should push harder, and draft a three-email post-purchase sequence timed to land before customers usually drift away. No discount codes in the first two. Then suggest three A/B tests for the flow, each judged on second orders, and rewrite my survey so every question is tied to a decision I'll make."
Rebuild your post-purchase flow around that timing, and set up the first A/B test.
Run it for one full reorder cycle and compare the repeat rate with the cohort before. Then run the next test.
Read next
Retention closes the loop. When customers keep coming back, you can afford to pay more to win new ones. That feeds straight back into traffic, and the whole machine compounds.
The full process: The Optimisation Toolbox
The mindset behind it: Why Optimise?
Not sure which lever to start with? Take the free Optimisation Audit to find your biggest marginal gain. If you'd rather have a hand putting it into practice, you can work with Ian.