Reheating stuffed zucchini can take anywhere from 15 to 25 minutes, depending on the size of the zucchini and how it has been prepared.  When reheating, preheat your oven to 350°F and spread the zucchini out in a single layer on a baking sheet. Bake for approximately 15-25 minutes or until the stuffing is heated through.  If desired, you can also add a topping of cheese during the last five minutes of baking. Be sure to keep an eye on it as it reheats so it doesn't overcook.