A second Mean Girls? I doubt it because the first one more or less ended with closure to the whole story... unless it will focus on the 'Junior Plastics'... but all that would be is a copy of the first one with different 'mean girls'...
The first Mean Girls was ace (thought it wouldn't be my thing but was, ooh got to put that in the other thread), but a second one wouldn't work so well. Although it's Hollywood..they milk successful films like nobody's business.