Use this script to clear the Skype / Lync autodiscover cache for a user.  This is useful if you are updating / moving to a new Lync/Skype infrastructure but not performing a hybrid migration.  Lync/Skype cache server location data in %UserProfile%\AppData\Microsoft\Office\Lync and %UserProfile%\AppData\Microsoft\Communicator. If the Communicator, Lync, or Skype cache is not cleared, the client will attempt to autodiscover to the values stored in the cache.

For more information on the script, visit the blog at https://www.undocumented-features.com/2018/02/20/clearing-skype-cached-data/.