To reheat lasagna, preheat an oven to 375 degrees Fahrenheit, use fork tines to pierce the top of the lasagna all over, pour 2 tablespoons milk across the top, wrap the pan in foil, and bake for 20 minutes. Check to see that the cheese is bubbly and golden.
When the lasagna thoroughly heats, the tines of a fork inserted into its center for 10 seconds are warm to the touch. After 20 minutes, if the lasagna is not properly heated, cover it in foil again, and bake it for an additional 10 minutes. Serve reheated lasagna immediately for best results.