GreenCookie,

Sujaata is right. As long as you are going to college maintaining your F-1 status with a valid I-20, and don't intend to travel to outside the country, you don't need to renew your visa. If, however, you I-20 is expiring, you need to go to your International Office and get it renewed, which is not a hard process.

Hope this helps. Good Luck!