to all...
merely using AP to reenter while you are working on H1 does not invalidate the H1 (only using EAD does)... you can search these forums for detailed discussions on this subject. this rule has been in effect since june of 2000, to the best of my recollection.
if your H1 extention has been approved, you can apply to st. louis for stamping. i have heard that these days, st. louis is not being very cooperative, though (again, search these forums for details.)
to Rahul_need_help: if you already have another job lined up with a new employer, have them file an H1 transfer application for you before you get laid off, if you want to continue working on H1. once that app is filed, you could switch to the new employer while it is still pending. if there is a gap in your paychecks, i.e., you get laid off first, and then an H1 transfer is filed, then H1 transfer could be denied, as your existing H1 becomes invalid as soon as employment is terminated (so there is nothing to "transfer"). in this case your employer will have to file a fresh H1 application and you will have to wait for its approval before you can start working. then you would have to use your EAD since you surely would not want to remain unemployed all that while.
DISCLAIMER:
i am neither a lawyer nor an immigration expert, therefore the above should not be construed as legal advice or recommendation. please seek advice from a qualified immigration attorney before making any decisions.