Now I have a doubt: I add a little of power ups or work at something completely different?
I'd say this is a matter of philosophy. I'd strongly encourage to move on to completely something else so that you can begin fresh. That removes "mistakes" from the background of your previous game. You need to think again the things you learned in the previous game. Starting anew also forces you to reactivate some of that creative mind that you don't use while you are in the coding part of game design.
There is also the approach of further building the previous game. I've experienced that it is not as educational as my suggestion above though.
So I suggest moving on to something new and different. Something that forces you to learn a new aspect of Construct.