The classical limit is retained in QM by construction in a very general way. If the problem is determined to be a classical one, the physicist never solves the problem in a genuine quantum-mechanical manner, then draws the classical conclusion from the complete quantum-mechanical solution.

In the case of many-body problem, the equation for the center-of-mass wave function can be separated from the rest, which again quickly reduces to the classical limit. But all of these are by construction.