I have a depressingly destroyed lawn. Partly dog damage, partly lack of care.

Its mostly buffalo, but some couch self seeded and grows better than the buffalo does, so i’m inclined to leave it and let the two types grow where they like it most. Is this a good idea?

We are thinking to get some top soil, but don’t know what time of year to put it on.

We also need to replace the sprinklers, but i haven’t really found a type/brand that i’m happy with yet.

Any ideas and advice anybody has would be greatly appreciated!