Do you have dataconnections to the server where qlik sense is installed? In a full standard installation with only a central node the monitoring apps would use localhost instead of the fqdn so you wouldn't need to change anything here.
You want to check the if the repository service uses localhost in the connection string or if it uses the fqdn, without changing this if it's fqdn sense wouldn't start up after the change.
An appbackup however is not needed, but a database backup I would do. That is also an easy way to restore all with a reinstallation in case something goes wrong.
