Is the new motor an identical part number to the original ?
In most systems, the motor data is stored in the motion controller or servo controller. If that data is still stored, and the new motor is physically the same as the old one, then there's no need to re-tune the system. The commutation and feedback and resolution and signal and inertia and magnetics are all the same.
Certainly sometimes a motor fails because other parts of the system have degraded or changed, and tuning the motor to account for new loads or dynamics is appropriate.
And I have worked on systems that were so sensitive that replacing a blade or bearing would require re-tuning.
But in general, just replacing a motor does not require re-tuning a servo controller if there have been no other changes.