visa extension question - need help!

My daughter, a U.S. citizen, has been in China on a tourist L type for nearly two years. She has been leaving PRC for Hong Kong every 3-4 months (whatever is required) then returning to PRC. Her two years is up in August. I should mention that she was born in PRC if that matters. She wishes to remain in PRC for another six months although her preference would be to have the ten year L type. Is there any way that she can remain in PRC and extend her L type without leaving for the U.S. to do it?