Updating from one Motiro version to another is pretty hard right now (at least if you don't use Subversion for that). There could be a script on script/update (for example) that would

• Download the most recently available version (without relying on Subversion)
• Back up the user data (database.yml, motirodb.sqlite, motiro.yml, etc.)
• Unpack the new version
• Restore the data
• Migrate the database to the new schema

There may be some more steps needed between these. Investigation is needed.