What's the most effective way to turn existing customers into repeat customers?

To give them the best for there money & a very strong inclination towards understanding the customer needs. Once you understand the need then try to give them the product & service which exceeds there needs. A constant soul search on what customer needs & how best you exceeds the need in the best price is the winner. It's not a one time affair but a continuous exercise which goes on for for ever. Business scenario is very dynamic & it changes very rapidly. Company has to act faster than the changing times to understand the ever changing need of the customer & adapt quickly to market requirement. The real winner is to make a near correct assessment of changing needs of the market & adapt the changes before others could do it.