Don't know what to do.. the torrent download looks the same, but I'm clueless about the whole thing.
Set the torrent to download into the same directory you installed the beta client into (uncheck icon.exe from the torrent, it's an old version). If you used NCSoft launcher to download it, the directory you need to choose is NCSoft - by default it will be in C:\Program Files\NCSoft or C:\Program Files (x86)\NCSoft .
The torrent client will be able to recheck the data - don't start downloading the files right away, use the client's "force re-check" option (most of them have one, uTorrent definitely does).
You will see which files differ from the ones described in the .torrent file - they will display a progress rate that is below 100%. When you start downloading the game in the torrent client then, it will download only the data your copy has corrupted / missing.