Are there no other horses available for you to ride? Why are you hesitant to use a crop and spurs? Neither are harsh provided you know how to use them. I ride all of my horses in spurs just so I have the option if I need to put it on.
Anyway...carry a crop. Ask your pony to go up to trot once with your leg. If he doesn't respond, put your reins in one hand and smack his firmly with the crop behind your leg. The crop is NOT a tool of abuse - it's an extension of your leg.
He needs to learn that leg means go. However, I caution that he's a SCHOOL horse. He's meant to have inexperienced riders on his back that don't yet know how to effectively use their leg. As I said earlier, look into other possible mounts.
There are other horses, but this is the one that I like to ride. Plus, all of them are lessons horses, so it wouldn't really matter.
The thing is, because she's ridden by little kids, she really dislikes the crop because they overuse it. And I don't want her to become more crop dependent, as she is now. The only way I can get her to go nowadays is if I have a dressage whip, and she hates it.
I was looking for a way to maybe reverse the desensitization, and I will try what you said with cropping her if she doesn't listen to my leg cues.
Another peeve that I have about crop and spurs is that if you use them all the time, you become so dependent on them that you can't get them to go without it. I realized this while watching other people ride, most the people I know probably can't even get the horse to canter without a crop in their hands. I don't want to become like that.
Thank you though, I will try what you said : )