Do not strike the trot or canter facing the jump. Instead, trot a small, half circle to the jump, then halt afterwards. Back a few steps, then either turn left or right and do it again. Change up the directions every time, sometimes skipping the back if she calms down, but always halt.
Another method, do circles and dressage patterns throughout the arena, surprising her with a jump every once in a while. Make sure you're not approaching in a long straight line, or she'll catch on and anticipate. Similarly to the exercise above, make sure the jump seemingly comes out of nowhere, and afterwards, work and work and work on something else until she forgets about jumping. Once she's calm again, then you can try and jump again, repeating this process.
The next method worked wonders for my old pony who got strong when the jumps got high. Keep in mind, this shouldn't be done every single jump. You could interchange it with the first exercise, too. As you approach the jump and you feel her start to build, turn and circle until she slows. Do figure 8s in front of the jump until she's calm, then jump.
Another thing that helped, was I'd halt my mare if I felt her charge the jump, back her up very quickly, then jump from a standstill and halt before she took a stride away from the jump. Now this is like a slap in the face and I only used it if she was charging through my aides. Use this in extreme situations, as if to make a point. Then, resume circles or whatever and go back to the jump.
Changing up their normal course of movement helps a lot. If she knows that heading straight for a jump means we're going to jump it, then barrel straight, or around a turn, she'll start to expect it and assume that's what's happening. If she has to keep guessing what path you're going to take, she can't rush as easily.
Keep in mind, also, that rushing is not always a 'love for jumping' as many assume. It can be a result of fear, holes in training, and just simple disobedience. Do these exercises from a pole, to 12", to 18" and so on, gradually getting higher. Do not raise the height if she is quick.
“Have fun - Stay on top.”
"There's nothing like sixteen hands between your legs"