There is a supposed interview from Mark Thornton on the TDI Wiki. It claims that there will be new characters in Season 3. And it makes it sound a little like some of the unused Season 1 characters will return.
http://totaldramaisland.wikia.com/wiki/Forum:Interview_with_Mark_Thornton
There isn't any confirmation that is real, but it sounds pretty believable to me. I might actually contact Mark on his blog and ask if this is a real interview.