Plain toast that has sat around for a couple of days, then reheated, doesn't taste as good as freshly made toast. So, with that said, if there is any leftover toast, it can be put into a plastic bag that is sealed off tight so no air can get inside for a couple of days, but it probably won't taste very good. Instead, take a piece of toast and cut it into cubes. Then you can make croutons. Another suggestion is to use some of the cut-up cubes in your meatloaf recipe. You can also freeze the croutons for later use.