Visa Renewing Issue

Hello,

I would like to ask few questions.

I have F type for doing an intership here in China. I got it for 150 days in Lithuania before coming. All this period, I haven't moved out from mainland. However, it is going to be expired in the middle of February. I am already thinking of applying for a new one and continueing my intership.

So, is it possible to apply for a new one here without leaving mainland? and get it for about 6 months lenght?
Do I have to change the type of F into M? as I was informed that F is no longer valid in general. Am I right?

Thank you for your response.