One thing that helps me when I’m moving up is to do the new height in a rollback. I like both fences of the line to be the same new height and create a rollback type turn to the first jump so that I have something more pressing to think about than the fence at the end of it. Nothing too difficult or technical of a turn, but enough that I can’t just think “I’m going to die. I’m going to die! I’M GOING TO DIE!!” on the approach and then dive ahead of my horse when we finally get there. It also makes me think “Impulsion!” on the approach through the turn, because my favorite thing is to tense up and make every stride shorter and shorter than the last one was when I get nervous, so I end up chipping in with no energy to get over the fence. I just focus on keeping my eye on the next fence throughout the turn and keeping a consistent canter with impulsion and moderate collection, and then wait until I feel the jump happening instead of when I think the jump will be happening.
I’ve also found gymnastics to be very helpful at building confidence over bigger jumps, because being able to just keep still and know the striding will turn out lets me figure out that I will actually survive the experience when there aren’t smaller jumps in front to guide me.