The standard answer is to take the mealworms out weekly for 24 hours to let them warm up and eat. Personally, I've found that my fridge is just a bit too cold and mealworms did not do well there. Maybe your fridge is better suited. The most important thing is not to put superworms in the fridge.
I don't keep mine in the fridge most of the time. I try not to buy more than I can use in a week or so, though. I give them some food, keep them on their oat-stuff, and use them quickly. If I have to buy a large count, then I do stick them in the fridge.
I keep mine in the fridge usually. I take them out a day before I want to feed my leo so I can gutload them. For instance, my adult male leo eats on Wednesday evenings and Sunday evenings. So I take the mealworms out of the fridge on Tuesday to gutload. After I feed him on Wednesday they go back in the fridge and I take them out again on Saturday to gutload for Sundays feeding.
For the baby who eats daily, I remove a dozen small mealworms each day and gutload them for the following days feeding.