Can I use a Category F with M entry type for more than one trip?

I have used my existing F & entered China twice during June of 2012. I plan to enter into China on December 10, 2012 with a departure date of December 19, 2012. The issue date of my current F is 01MAy2012 & the "enter before" date is 01May2013 with a 90 "days after entry" for the "duration of each stay". Its number is F9113028. Is my existing visa good for my December trip, or do I need a new one?