You can't just 'switch' into a 141 school, however. To take advantage of the reduced training time, you have to go through the whole programme. In other words, it's too late for you now.
I've never really seen anyone save much time with a 141 school. Yes, the legal requirements are reduced for Private and Commercial, but nobody really does that anyway, and nobody will take a commercial seriously until you have 250 hours anyway, so don't base any decision on that. You should get the BEST training you can, regardless of where. If you half-ass your training to save money, that's setting you up for problems forever.
PS - Stop calling it a 'PPL' unless you're not in the US. There's no such thing as a PPL here. It's a Private Pilot Certificate. There is no 'license'.