Relations 2.0 uses e4 technology and the p2 provisioning platform for software installation whereas earlier versions used the Eclipse Update Manager. Because of this circumstance, there's no easy way to upgrade from Relations 1.3 (or earlier) to Relations 2.0.
The simplest way to proceed is 1) to backup the data, then 2) uninstall/remove the old version of Relations, 3) install the new version and 4) restore the data into the new Relations version.
To backup your data, start Relations (the old version) and open the database you want to backup. Then start the Export... wizard from the Data menu and select Backup data. The dialog page displayed after allows you to enter the Zip file where the embedded database is backuped.
If you have stored Relations data in various embedded databases, you have to repeat the backup for every database you've created.
Save the backup file (or files) to a secure place (e.g. a memory stick).
Uninstalling the application depends on the OS you use.
Basically it means to delete the Relations sub-directory in the directory where you installed the application.
If you had used the Windows installer, you can use it again the remove the installed version of Relations.
See the installation instructions for the various OSs.
After installation of the new Relations version, you have to restore or import the backuped data. Restoring means you will overwrite the data of the opened Relations database with the backuped content. Importing means that you create a new embedded Relations database and copy the backuped content to this new database.
For restoring, start the Import... wizard from the Data menu and select Restore data. In the dialog displayed, select the backup archive containing the data you want to restore.
For importing, start the Import... wizard from the Data menu and select Import database. Name the new database you want to create and fill with the content of the exportet database. (Note: you can't choose the name of an existing database.) Then select the backup archive containing the data you want to import.
Most probably you want to create a search index for the imported the database, therefore, tick the checkbox on the import wizard.