Shut down any open Visio files. Backup a copy of the old map file. Open the old file and click the "Migrate" button in the eVSM toolbar. When the migration run is complete, your old file as well as the migrated copy will be open. In the old file you will see highlighting on any items skipped by the migration.
Migration is not a 100%, so you will need to do some manual work to finish. See https://evsm.com/evsm-v11-migration for a list of the additional actions to complete.