You are qualified to get a work permit extension IF you already have your certificate of nomination. The AOR or file number from the CIC will qualify you for a BOWP.
Sorry, you cannot use your AINP file number to get an extension. I guess your only option would be to have your employer file a new lmia for you. However, if your job falls under NOC O or A, you are exempted from the four-year rule. ^____^