Itouch battery keeps dying quicker when i use apps?

My 3rd generation itouch dies quicker when i use apps, i even turn down the brightness to minimum and it tends to die rather quickly, others have their brightness to max and their's work perfectly fine, i have a bunch of paid apps and stuff, and like 700 songs, my memory is pretty much full, is there anything i can do to get my itouch to have normal battery life again with the brightness at max