Register your Smart Trip and if you put a lot of money on it, you'll get a new Smart Trip (-$5 for the cost of the card!
Smart Trip will also allow faster exits out of Metro Parking lots.
Sometimes, if you have less than the trip allows on a Smart Trip, it will let you have a return trip on it. However, you have to reload the card before your next trip. When you reload it, it will subtract what you owe (trip cost - what was on your card at the time), from the card.
When the stadium opened, you could get one like my Avi!