Flat work is everything. I do lots of serpentines in the Trot after I've warmed up to make sure I've got her listening. Then starting over poles I'll gently halt afterwards, but allow them to carry on and canter in a circle once they are accepting over/ after the pole so you aren't halting every time; and I'd do the same over fences
i personally have never done this for this reason, but something that seems to get the horses I ride thinking more about their feet and focusing more is to go toward the jump as if you will jump it but before you get too close (at the same time making sure they obviously see the jump and get excited) to turn them out do it and circling at it again and just keep doing that until they are cool and collected while approaching the jump. normally this is some when a rider gets a bad distance but it could work for this too.
I am working with the same issue with my horse. We are doing lots of gridwork (with both poles and jumps so he needs to actually think where to put his feet), halt or walking straight after jumps, and in a line put a pole one stride away each jump and trot to the first pole and between the two jumps.
Lea Atwal I have never had a problem with any of my horses stopping after the jump, you only do it until the horse stops taking off and when he can stop without a problem you can either just make him trot after the jump or he should learn not to take off, it's a technique I learnt at a clinic
Pole work, grids, one thing I do is grab 2 jumps (or more if you like) a few strides apart and make your horse stop after the first jump before he jumps the 2nd jump, he's not allowed to do the second jump until he stops before it
Keep her at a trot and make long big slow posts over a pole and jump, keep the pole at least a 1 or a half a strid b4 the pole, you could even put 2 trot poles b4 it, then as she gets better make them canter stides
Do lots of halting transitions and downward transitions. Once your horse is listening try halting a little while after the jump and try to stop straight from the jump. Also time with this will teach the horse they don't have to rush!