Some plugins will “clean” their data if you delete them, so it’s possible if you delete the plugin and then re-install the same one that you’ll lose data. I recommend just uploading the new plugin and replacing the old one via SFTP.
The plugin developers offer support and automatic updates for the licensing fee. I cannot confirm this of myself, but the plugins on GPLDL should be the exact same. I’ve tested 1 via checksum and binary comparisons. The binary comparison was exact, the checksum was not only due to file datetime stamps.