With retail sales slumping in a difficult economy, many stores are running sales and providing significant loyalty discounts. Typically, they would offer something like $20 off $100, or another promo based on single-day purchases. However, I’m surprised to see that almost nobody is offering cumulative purchase discounts.

What am I talking about? Instead of just rewarding people for buying stuff that day, provide a sort of “punch card” that entices you to spend say $500 over a certain three month period, or simply make a purchase of any amount five times over that span. In exchange for doing so, perhaps you receive a $75 gift card or an equivalent discount. The idea is to get people coming back over and over, rather than cleaning you out one day and never showing up again.

Sure, this sort of thing might already be offered to people who have the store credit card, or have previously signed up for a loyalty card. But I think they’re missing out on a lot of additional sales from the much larger group of shoppers who come in because of a single promotion — and who might become loyal repeat customers if they’re given the right incentives.