Prolong 150-Day X2 visa to travel?

Hi everybody,
I am a German citizen currently studying in Shanghai on an X2.
Unfortunately it is only for 150 days (everyone else seems to have 180) which would stop my plans to travel a bit when the semester is over.
Does anyone know if there is a possibility to prolong that visa for a short time or maybe get a tourist L from within China?
Thanks ahead for the answer!