My old lease horse did this all the time. What I did is go at the jump at a canter, jump it, and immediately stop him and back him up a couple steps. Do this quite a few times and it will help and you'll notice a big differnce!
One of our horses do that. What we do is set up a bunch of jumps in a row. Or after the jump stop and back a couple of steps.
My friends has this problem and every time her horse does this, my instructor tells her to halt him after the jump and back him up
In pony club if a horse took off after a jump we were asked to halt the horse after it had jumped, seemed to work as you are giving the horse something to think about
Just put poles before and after the jumps and also halve halt ur horse just before the jump.
Put poles before and after the jumps and so a lot of gridwork.