travelling while asking visa extensions

Hi all,
I will ask an extension for 30 days to my business M type (i just realised they did not grant me the 90 days required while i was in China already), but it looks like it will take 7 working days to get the extension. Right at that time where I will ask the extension to the Office in Shanghai, I need to travel to Beijing with air and hotels already booked. Is it feasible if my passport is with the authorities in Shangai?
Elisa