XBT, Pjiang, and other experts: Please tell me the best way (abo

My I-140 was approved, I-485 is pending and H-1 (6yrs)expires Feb.2008 If I am going to China for a visit, when is the best time to go and what is the best way to keep my H-1 before I get GC? Should I extend H-1 after visiting China and before AP one yr expires? For example, I apply an AP for visiting China in Dec 2007, and extend my H-1 Sep. 2008?

Thanks a lot in advance!!!