In that case, there is no need to kill the civilians any longer. If two technologically advanced nations battle each other, and the robot fleet of one of the nations is destroyed, the battle is lost. Still fighting would be pointless, because you lose people, and the other guy does not even lose machines.
So we'd just have a huge robot battle in the desert that we could watch on TV, and when our country lost, we'd resign ourselves to the invading force and just give up (or run).
I guess the strategy then would be to wait till the human military administrators come in, and then start a low level insurgency.