How old is he? They can go for quite a while without food - being cricketless for 3 days or so shouldn't hurt him.
Do you not have access to a pet store for feeders in the meantime?
Strange, but I've heard that they can have baby food which you could get at the grocery store, however I don't see what the nutritive value would be in something like that for a leo, and because the food doesn't move (at least hopefully not

) it probably wouldn't elicit a feeding response. So there's probably no point in that..
You might be able to try earthworms just to get something in him (cut them up if needed) perferably purchased or at least taken from somewhere pesticide free. I did this for my tree frog when I couldn't get out to the pet store, not sure about a leo.