Double Entry M Visa

Hi,


I have a double entry (M) with maximum stay in each entry for 30 days.

I entered China (1st entry) on 13th February 2014. Now i need to go back out of china before 30 days and i can re enter using the second entry available on it.

Is it possible i can use the second entry without leaving china. Can this be approved by PSB.

If yes what are the documents Required.

Thanks