some things for you to try...
-put some fruit in the crickets box, this will make the crickets have a higher water contant, therefore hydrating your gex
-spray the sides of the tank daily (they will lick the water off the glass sides)
-dust the crickets with calcium powder, and possibly vitamin D powder if you can get some from a petshop .
-give them some sunlight - but do not leave them in the sum for more than 5 minutes - they can die from heat exhaustion VERY quickly
-make sure they have enough heat (if needed, get a bigger heat mat, or have less substrate)
-make sure they can escape this heat
-try offering them slightly smaller crickets, or put the crickets in the fridge for 5 minutes before you feed them to your geckoes, this will make them less active, and the lizards will ude less effort to catch them
if you do all this, you should be on your way to having healthier, happier, plumper geckoes ...