We were able to do upgrade to 3.2 from 3.1 and below are the steps
1. Repository password should be available with you
2. You know which kind of Persistence you are on, Shared/Sync persistence
1. Backup Certificates SSL, both client and sever certificates<Detailed information is mentioned in help section of Qlik>
2. Backup Site <Logs, Apps and other stuff>
3. Get .exe file of latest version of QlikSense and upgrade the application
4. Post upgrade, applications will be automatically migrated to new version
5. Open Hub and check applications, Data connections.
That's all you have to do, hope it helps!