Check out NcFTP Client (is available in Debian repository)
Also look at The NcFTP Overview at IBM developerWorks (note the Recursive Transfers section).
Actually it can't run in daemon mode. To make periodical downloads you have to write a tiny bash script like:
ncftpget -R -u username -p password ftp.example.com /local/torrents /remote/torrents
And then run it in Screen or dtach session to prevent terminating upon closing of a terminal window. In fact you can use any console FTP client you like with such a script to do automated periodic downloads like this.