Visa Dilemna

Hello - I am in Shanghai visiting my Chinese girlfriend. I am on a 90 Tourist L type which expires on mid Feb 2016. In order to get this L type I had a letter from my boss giving me 90 days off, a letter from my girlfriend and a letter from her father!

Right, so my problem is this - I have found a company to work for and they will apply for a Z type for me, but my current L type will run out before the Z type is granted (assuming it will be!). Can I extend my tourist L type, and if so can I extend it by more than 30 days? I am concerned they will not accept my extension request because they will want to see a return flight (and I do not have one).

Any help would be greatly appreciated.

Thank you