I get where you're coming from. Sometimes it is hard to stay focused. I, for example, am not looking forward to a shoot that I have this weekend. I am photographing a concert and I need to take close-ups tomorrow night during dress rehearsal, and then shoot live on Saturday and Sunday. The reason I don't want to do it is because of the level of dissatisfaction and disdain that I have for the quality of the production from purely a musical and performance standpoint (I am a theater geek, actor/singer/playwright). I joked around with my daughters that I will just listen to my ipod while I shoot and I won't have to listen to it!
But seriously, I feel that's it's best to walk away for a bit (except for the school work - as to not effect your grades). As it's been said in other posts, if you love it... the passion will find it's way back to you.
A quick personal experience: I decided about 6 months ago to go and practice some night time photography (I wanted one of those blurry, 30 second car lights, highway shots - you've seen them, where you see light trails driving down the interstate). I put the camera in the car, got the tripod out and drove around for 2 hours and I didn't take a single photo. I totally crapped out. No inspiration at all and it wasn't for lack of potential locations, I just tried to force it. So, I think it's just like everything else; you go through stages. You eat a lot of Italian for for a few weeks and "poof", all of the sudden you don't want any more and you go for Mexican food. Not that Italian is bad... you'll eat it later, it's just not the food you crave today.