There are several fast and yummy ways to get rid of your leftovers without them resembling the original meal. For instance, Sunday's roast chicken with rice and a salad, Monday's pot roast with mashed potatoes and veggie medley and Tuesday's Spaghetti and meatballs with salad can be transformed like so: Wednesday chicken fajitas with fried rice (Sunday's chicken cut up with peppers and onions and seasonings added - plus leftover Sunday rice with chopped onion, garlic and seasonings aded, and tortillas), Thursday beef stroganoff from the leftover pot roast adding egg noodles, mushrooms, sour cream and seasoning. Friday's meatball sub - just add cheese and a bun! Salad components are generally stored separated and can show up again as a side dish for any meal and veggie medley can be added to a casserole or just show up as a side dish again. Re-used side dishes are better if served with a new main course than with the same main course again.
Things to consider when re-using leftovers:
fajitas, quesadillas, enchiladas, etc
homemade pizza (any style)