It's illegal to "penalize" you for leaving (not that apparently your company cares anything about the law, H1B is not to be used as you currently are using it). They can sue you for the actual costs that getting your status cost them that they didn't recover. It can be a few thousand. Frankly, I'd file a wage claim, they're not allowed (no matter what the contract) to withhold the "liquidated damages" from your pay. They'd have to sue you.