Im Pakistani right now working in China holding Z visa which is going to be finished on 7th of August. What I need to do Z visa extension within China?

hi sir,
Im Pakistani right now working in China holding Z visa which is goin to b finish on 7th of August, what i need is that i want to extent it for more 1 year n the problem is that my company can not help me to get extension. can u plz guide me about my problem how i can solve it?

Thank you

Rana