Today's frugal tip is to save money by maintaining your dishwasher. Make sure you are cleaning out the food debris tray often. One way to clean out your dishwasher is to place a cup of white vinegar into the dishwasher dispenser and let it run while its empty.
One problem that could be causing you to need to run your dishwasher more than once is not emptying your garbage disposal prior to running the dishwasher. Run some water and turn on the garbage disposal to make sure its completely clear before your start your dishwasher.
If you find you are still having to rewash dishes that have been washed once in the dishwasher consider getting a rinse agent like Jet Dry or Oxy Clean's Dishwashing Booster. If hard water is to blame consider purchasing Lemi Shine at the grocery store or at Wal-Mart.