Leopard geckos feed primarily on an insect based diet. This diet keeps them active and interested in hunting most of the time. However wild leopard geckos eat all kinds of insects (anything that fits in their mouths) so
Feeding your leopard gecko the same type of prey week in week out can have an effect on the activeness at which it hunts prey. Feeding the same insects can make the gecko go off its food and not eat as much as it should.
Leopard geckos are usually easily stimulated by the variety of food on offer and by the way you present the food to them. Offer differrent types of prey to your gecko and you could see a more active hunter. I use a feeding schedule a little like the one below. It may be very basic with just 3 prey items but it has really been successful in stimulating natural hunting and my leopard geckos are very active hunters.
Wednesday: Locust (Waxworm every second week)
This is a simple shecdule but you replace aspects with other live foods such as mealworm. So if your leopard gecko ever goes off its food, try them on something else. It could be bored with its current food and wants a change.