Updating TSP from version
The Scheduler do not removes any data from database during update/disabling/uninstallation. What more, update of plugin performs automatic data migration.
If you upgrade JIRA plugin we recommend you upgrade to the latest available version before updating JIRA. After installing a new JIRA you may need further update the plugin, but it will be faster and data migration will be more stable.
Backup
We also recommend to make backup of Scheduled Issues before updating TSP. This is additional step which allow you to save all data for case of any migration problem. Here you can find information about exporting backup: