There could be a few things going on.
I've read that after about 1 year of age, their appetite decreases, and you could start feeding them every other day. I'm sure it varies with each cham, so you should judge by your cham's appetite..
Another thing it could be is he's being picky or spoiled. Have you given him treats like meal/butter worms as of late? Perhaps he's holding out on the crickets because he wants dessert.
Another thing could be that he's getting tired of crickets. Have you been switching up his diet? Dubia roaches, pheonix worms, grasshoppers, flies, moths, small mantis? That could be something to consider, variety to peak their interest and also to improve their health
Just so you know, my guy is sorta going through the same thing, so you're not alone. I'll throw some dubias and/or crickets in there, and he'll just stare at them. Other times, I'll catch him eating a dubia here and there. Basically I keep it available, and it's up to him to eat.. One things for sure, if I put a meal worm in my hand and offer it to him, he NEVER resists no matter what time of the day it is.. So i know he's sort of spoiled.
Actually, that gives me an idea, if you truly concerned with your chamn not eating, offer it a treat like a meal or wax worm.. However he's comfortable, whether that be hand feeding, cup feeding, etc.. Try that and see if he goes for it