Automator upload to ftp

I already have a way of uploading to ftp via automator the only thing is it uploads all the files in a folder.

I want to make an automator action that will allow it to only upload new files. like how the publish to iweb option only sends the pages that have been recently changed

does anyone know what actions would work or are avail so i could do this.

attached is a pic of what i have so far.