回复：To 863211:I94-cont.

I already used up 6 years limit. in 2009 my I-140 get approved so I had extended 3 years until 2012. Now my PD is current and will file 485 August.

 如果我在递485之后再延期, 则只有一年; 如果在递485之前延期, 则可三年,is my understanding correct?

-Not correct. It does not matter whether you file the H1 extension before or after you file I-485, you only can extend your H1 for one year because your PD is current.

可以自己做延期吗?

-No. Your employer needs to do it for you.

another option: can I travel to Bahama and come back in order to get a new I-94?

-No unless you are Canadain citizen or you have a valid H1 in your passport.