When leos are full they usually stop eating on their own. Sometimes they look like they can eat forever, but they will eventually stop.
I keep a dish of mealworms in their enclosures/shoe boxes at all times so that food is always available, even if I only feed them crickets every other or every 2 days, they'll always have mealworms.
I also keep a small juice cap full of gut-load in their enclosure/shoe box. Thats for the crickets to munch on and not the gecko in case all the crickets aren't eaten up. They'll eventually get eaten when the gecko is hungry, but this way it keeps the crickets gut-loaded and not bothering the gecko. 
Shayna
Leo Lovers Lizard Lounge