I have an above ground 21' x 48" high pool with water in it. It's approximately 1"-1/2 out of level on one end possibly 2". There are 4 post that need lifting and I really can't afford to drain it all the way, is there a way to drive shims or lift these steel post in some way, thanks desperate for some ideas.

Sorry no, draining it is, how it works, and then level, and then fill partial with water, checking liner position and leveling as you go along.