Using smart FTP to help create virtual back up of hard drive

I'm using SmartFTP to upload the contents of my PC's hard drive to my web site as a virtual back up.

I'm currently in the process of uploading all of my files for the first time. But in the future, I would like to only upload files that have changed. Is there a way to tell SmartFTP to only upload files that have changed since the last upload?

Thanks.