imo - if you know you're going to abandon a colony in the near future, then stop building things on it.Captain Fizz said:Would it be better to keep upgrading the 135 field planet until it's full, or just leave it producing res (& BS) until a new planet is required?
EDIT - Oh, and would it be worth building a nanite on it if I am going to delete it in a few weeks/month?
Just let the mines get as much of the resources you'd spent back.
It takes weeks or months for the later mine levels to repay their cost - so move the resources to another planet.