My baby dragons don't eat very much at one time and will only eat in their enclosures so I free feed in their dishes. But the dubias aren't very active and I sometimes wonder if my babies would be be intrigued to eat more if they saw them moving more. Several times per day to wiggle the dish and add fresh veggies to get them active but would anything make them more active all day or more of it?
I usually only see them active in my colony when there is fresh food put down. You could try putting them onto a salad. They seem to especially like squash. When I feed them I usually release them one or two at a time and let my dragon hunt them down. I just repeat for several minutes until he starts to lose interest or starts hoarding them in his beard after chewing.