Yes, try a whip, or spurs (but don't ride to much in these)
I have the same problem. Ask one (with a push of your leg) ask again, (kick this time) ask a third time, (use the whip behind your leg)
This is not a case of animal cruelty. Its called making a horse work, and listen to their rider. If you just went around with a little nudge the whole time, yes your horse will think it can do what ever it wants.
Let her travel around at a nice forward canter, or trot, get off her back, in a jumping postition (2 point position) and then bring her back to a slow pace, then make her go faster again. Repeat a few times, then back to a walk on a loose rein.
Good luck. Im sure other people have other suggestions. But that is what I have been doing with my QH, he has no impulsion what so ever, and hates dressage.