Can i get an extension stamp on my old passport?

Hello sir my name is Shakeel Ahmad and I am a teacher in China, I recently applied to renew my passport at Pakistan embassy in Beijing and it is going to take almost 4 weeks ,but my visa expires on 6th of April. I don't think I can obtain my new passport until then so kindly let me know if I could get an extension stamp on my old passport in order to apply for Chinese visa. Moreover tell me how much is the fee for this extension stamp. Thanks