See i'm new to this Jam stuff but what i've found is how much it pushes you to add the next piece to you game so can that be done here?

Can you submit a game your building with the idea that you are going to add to it and that bit can get voted on?

Sadly not. The idea here is to do it from scratch as much as possible.

You can always make that new idea you have as a standalone project, if it makes sense within the game jam's themes, and then implement it in your own game. You know, treat it more as a kind of test run for something you want to add to your personal project.