We do offsite installations and upgrades, message sales@nodebb.com
Of course, we do have docs so you should try it yourself just back up everything first!
Edit: to answer your original question, we do plan on building an upgrade button into our hosting plans control panel - right now we just upgrade customers manually. It's probably impossible (or hard) to make an app upgrade itself via acp, we would need to make the acp a standalone application (we've toyed around the idea, but not worth the development time)
