Hi. There is no change in the process, that step is still needed.
That step is not for the refcounts, though depending on your service and your model those may change, they are for the diffsets. The diffsets on the service will contain information from the old NEDs and the re-deploy performs that migration.
If there are performance reasons or other reasons you can postpone that redeploy or spread it out over time a bit, but you want to do it before you remove the old NED. If you use get-modifications or similar you definitely want to do it fairly soon. It also serves as a check that the service works okay with the new NED.