H1b to L2 and back to H1B

I was in States on H1b for around 8 years and then moved out (no particular reason). I had approved i-140. Now my wife company wants her to go to states on L1 visa and i can come along on L2 ( and possible work on l2). My question - once i am back in states can i change my status to h1b using approved i-140? If so would it be cap exempt since i have already used up my 6 years on h1b

You should be able to change to H1B using approved i140. You should be cap exempted as your i140 was approved (make sure it has not been revoked).

I would suggest to probably use L2 EAD to work as it will have no restrictions. H1B has so many restrictions and paperwork that you will not like it.