My H1b got approved in 2021 from India and it got expired last month, I didn’t travel and didn’t go for stamping as well because my employer missed few experience letters.
Now I found another employer to transfer the petition and Is there any way to amend the exciting approved h1b to include all my experience.
There is no amendment in your case. The new employer have to file a new H1B petition however based on prior approval, they can request the petition under cap-exempt. There are chances that it may get approved under cap-exempt so you may not have to go for lottery process.