There are two types of repeat customers: One group repeats choice based on habit and another group repeats choice because of brand preference. The former is behaviorally loyal only whereas the latter also exhibits attitudinal loyalty.
A recent study has shown that cross-selling promotions that ignore this distinction are less likely to succeed. While the brand preference group can be lured with an attractive offer for the brand, habitual shoppers will not be lured by promotions trying to change their routine and may even develop negative brand attitudes.
Rather, this group must be approached with a strategy furthering their routine. For example, if a shopper shops one specific day per week, reward her for purchasing the brand in a different category several weeks in a row. A simple price-off promotion is less likely to be fruitful as it breaks an established routine.
Source: Liu-Thompkins&Tam (2013), Not all repeat customers are the same: Designing effective cross-selling promotion on the basis of attitudinal loyalty and habit, Journal of Marketing, Vol. 77 (Sep) , p. 21-36.