With mince dishes I alternate, so that one week it's bolognese, the next week will make lasagne (made double bolognese the week before), then cottage pie the following two weeks, but alternate the topping, so plain mash, pot & swede mash, sweet potato mash, sliced potato topping etc.
Alternate stew / pie / casserole bases, so tomato base, usually Mediterranean veg, creamy base, leek / mushroom, gravy base.
Chicken or fish pie I alternate toppings between pastry, different mash or sliced potatoes.
These are all fairly basic so you've probably already got these, but I tend to shop for what's on offer and then adjust flavours and veg / sides accordingly. Because the supermarkets alternate what's on offer, I shop for those, so tend to get a mix up that way.