LA CROSSE, WI- The La Crosse-based Kwik Trip convenience store chain plans to switch to prepay only at gas pumps starting next month.  The company says it is making the change so it can devote more resources to the in-store customer experience.  Right now, its employees are spending some of their time watching the pumps to see if a driver takes off without paying.  The change goes into effect January 3^rd.  Diesel fuel pumps will still have a pay inside option.  Customers will also be able to use cash or checks to prepay for fuel inside the store – and they can use debit, credit, or gift cards at the pump.