Are you still just dumping crickets in and walking away for a day or two? You did that last time you took a 3 day vacation. If you truly care about whether your leopard gecko eats or not, try observing. You are supposed to take the crickets out if they do not get eaten within the hour anyway. In fact if your leopard gecko does not show interest in the crickets, you should stop trying to feed it crickets. Crickets will gnaw on your leopard gecko and cause it extreme stress if you leave them in the cage for long periods of time.
These are things easy to observe if you just spend some time watching. And by now you should've tried mealworms to see if you get a better result. Or pulled the hind legs off crickets to see if crickets are possibly running & jumping around too fast. Again, spending a lil bit of time with your leopard gecko, you would know whether your gecko is even going after the crickets or not. If he is going after the crickets, then good, pull the hind legs off to make crickets easier to catch.
Temperature is a big deal as suggested above, they won't eat if there is either not enough heat or it's too hot and they have no temperature gradient. Sort of like you sitting in a house without air conditioning of any sort, with windows closed in 100 degrees heat, you would have no appetite to eat either.