Find out why your customers do not return. Make it easy for them to complain. Call them. Offer reply cards. Provide #800 numbers to call. Lure them with product offers. Email them your customer service response numbers to offer comments and file complaints. Make it easy for them to vent their frustration with your system. If you can reach them and get their attention, ask them to tell you what the one single thing about buying from your company that caused them to stop buying from you. Pay them, give them coupons on future purchases, send them small gifts for their participation but find out what is wrong with your company. You need to do this especially when you do not have a clue what is driving customers away.