change the VISA S1 to Z type

Dear Sir/Madam

I am Mrs. Jeeva Jothi Kumaravel from India. I am in china for last four months. I came here as dependent of S1 type. Now I got the Post doctoral position in Beijing. So I need to change the S1 to Z type. Is it possible to change it from china or else have go back to India to change my dependent S1 type to working type Z?