Simply download the zip from codecanyon and overwrite all files from your previous installation with ftp or unistall the plugin (free or pro) and install the new version again. All settings are stored in the database so you don't loose anything. Also use this way if you have used the personal version you can get on wordpress.org. If you have some radio elements empty after the update simply select the one you like and save again.

Also see: https://codecanyon.net/item/advanced-iframe-pro/5344999#item-description__upgrade

Have fun using Advanced iFrame Pro,

Michael