If you are going from TRS19 to Trainz-Plus (TRS22-plus), then the route will be incompatible with TRS19. This is due to the changes with the files to handle the HD terrain and other new features now found in TRS22-Plus that are not found in TRS19.
When updating, it's more than just recommended to keep a backup of an existing version until you are satisfied with the new version and have migrated everything over, and it's best to keep an old version or two installed anyway in case you need to test or check some differences in versions.