One secret (not so secret) method to get repeat customers is to force them.
I mean let your customers opt-in for receiving regular shipments of your fine products.
Jokes aside, creating subscription or recurring orders can be a solid strategy to ensure repeat orders.
The product type will need to make sense: replenishment products or the mystery-box subscriptions seem to work well.
You could start by taking your most popular two products that fit together and creating a subscription version of them. Even with a slight subscriber discount, this could be a profitable product line after the first few renewals.
Once you develop one that starts to sell, then you can start to experiment on a second offer and try to improve.
If you haven't installed Repeat Customer Insights yet, it's an easy way to get a detailed look at your customer behavior. With the Customer Purchase Latency report you can find the intervals customers are reordering at and tailor your subscriptions around them.
Retain the best customers and leave the worst for your competitors to steal
If you're having problems with customers not coming back or defecting to competitors, Repeat Customer Insights might help uncover why that's happening.
Using its analyses you can figure out how to better target the good customers and let the bad ones go elsewhere.