Suppose you have an object that has just left the atmosphere, and suppose it is in an orbit. You have the same problem again: every orbit repeats, so the object's orbit, having just left the atmosphere, will repeat into the atmosphere.

Let's put this another way: every orbit is an ellipse. If you do not alter your orbit, you will only travel on the ellipse. The moment you stop interacting with the atmosphere, you are on a fixed ellipse. The problem is just behind you on the ellipse is the atmosphere, and if you continue forward on the ellipse you will inevitably come back to the part of the ellipse that is still in the atmosphere.