Absolutely, you can make it the day before and keep it, covered, in the fridge until you are ready to put in the oven. Or, you can freeze the lasagna and thaw it out over night before cooking it 30 minutes. If you wish to pop it in the oven frozen, consider leaving it for an hour. Lastly, you can also freeze it once cooked and warm it up in the oven or microwave once unfrozen.