More concessions

If you can identify your biggest games of the season, try this:

Get a measurable bassline for sales (i.e., past sales from similar games) - if you don't already do this, you should be doing it every season for every game.  An easy excel file with something like the following so you can measure what you can expect in the future (trending) like:
attendance
weather
other events that day
team record
opponent
televised? Y/N
vendors?
concession sales?

These questions will let you plan accordingly for future games.  The answers will help you do everything from staff better and not waste money on unneeded personal to be able to charge premium prices for outside companies that want access to your fans.  You can also take it to the next level and put vendors at your largest games. 

Think about this:  If you are a parent and you bring two of your children to come watch the oldest play in their home varsity game, do you want to get up out of your seat and have to coordinate a trip to the concession stands?  I mean bathrooms are tough enough.  You don't have an assigned seat and you may not want to lose your seats so it would be absolutely convenient if somebody came to you.  I bet you'll see your profits increase and you'll get positive feedback from your parents that don't want to get up and stand in the long lines.  And, admit it, it adds great atmosphere to hear the sound of somebody screaming "peanuts."