The NES version of Rampage is a little more limiting than the arcade version. You still have a ton of cities to level, but you only have two continues (e.g. three lives) to go through them all, where in the arcade you could just keep feeding the machine quarters until you made as much progress as you wanted.

So what do you do?

Any time you run out of life, your character will shrink back down to human form and slowly work their way off screen.

Before they get there, if you hit the B button on your controller, they get their life bar back, and regain their former stature.

And you can do this as often as you need to, as long as your character didn't shuffle off the screen it still counts as the same life. So you can make it through all 128 days pretty easily.

But it will still take a while to do that.