I was playing and then my Froakie started to evolve and I pressed B by accident. I really want it to evolve, so is there any way to make it evolve?
Just level it up again and it will evolve. If you press b after a Pokemon tries to evolve, every time it levels up afterwards, it will attempt to evolve again. Source: experience
Just level it up again and it will attempt to evolve again. It will happen all the way to level 100, unless Froakie is holding an everstone in which case it will not evolve unless you take away the everstone. Hope I helped!