I may be off base but is it possible that you're getting disinterested with school? Kind of like a grade apathy.

Does any of the following sound familiar to you? You feel a 98 can be achived without really working, you find homework too easy, class participation is a joke, you know more than your teachers, you're wrongfully portrayed as thi great student (tacher's pet perhaps), teachers give you a break because they know you can do better, every year is the same song and dance.

If any of that sounds familiar you should figure why, and perhaps how you can fix that. In general though, it might be a good idea to make school more than just academics. Join a sports team or play production, tutor some kids that need help, volunteer some time for a good cause, that sort of thing.