Store the grilled corn in a sealed plastic bag or airtight glass container in the refrigerator for up to 4 days. If you won't eat it by then, you can freeze the kernels for up to 3 months. To reheat, place the cobs in a pan with 2 tablespoons of water and cover tightly with foil. Bake at 350°F for about 10 minutes until the center is hot. Check for a sour smell or slimy texture as signs of spoilage.