Sparky 2.0 - My 2001 Prius

My husband, tired paying an exhorbitant $1.35 per gallon for gas, went online in September 2003 looking for an additional vehicle to save gas and miles on our Tahoe. "Any requests?" "Yes, great cupholders and a decent CD player." Our soon to be Sparky had been returned after a 36,000 mile lease. BUT, also considered a return under the lemon law. Within one year (under warranty), the batteries had to be rebuilt due to a sensor from the gas cap had been cut by the previous owner. Just last week, the full battery had to be replaced after a ten year run (car was originally purchased in July 2000) but with only 61,600 miles. Technician suggested I drive the car more than the typical 5 miles short runs. Sparky is in great condition otherwise (only have replaced the tires and a drive belt). I would appreciate any suggestions to keep Sparky 2.0 running efficiently for another 8 to 10 years. Thanks.