If you can't find a shorter lease, but won't be on campus for the summer or something, you can always sublet your apartment to someone who is staying on campus. My advice would be to make sure that you know the person isn't going to damage the property because you will still be held liable. When I was in college, I always sublet to my friends who were staying for summer school. That way, I didn't lose as much money as if I had just left my apartment vacant, my friends had a place to stay and I knew they would take good care of it.

You need to be very careful and make sure that if you are subletting that your lease allows you to do that. Otherwise you could be considered as abandoning the unit and breaking rules by letting others live in the unit. I have actually seen someone sublet their unit and they thought that because they were subletting that they were not responsible for the unit, but the person who sublet never paid the rent.