I agree with bea and Amanda. 1m could be his max, and he's feeling over faced. If you want to move up, if reccomend taking a step back as Amanda said to further build his confidence, and then focus a large amount of time and energy on the flat. This will help him jump better. Just like conditioning and cross training for human athletes, working your horse on the flat should strengthen him and make him the best athlete he can be. Make sure that you keep in mind that he may not be capable of jumping a course of 1.2m jumps.