Install the newest version of SmartFTP on both computers:
https://www.smartftp.com/download/
If both systems use the same platform (x64, x86) you can use the Backup Tool that comes with SmartFTP (Start Menu->Programs->SmartFTP->Tools)
If not, manually copy the Favorites folder: %appdata%\SmartFTP\Client 2.0\Favorites from one to the other computer