How do i Synch Playlists in iPod Video to iTunes/or anapod?

i already removed the orig files in the PC harddisk and is only in my ipod video.when i add new sons to the ipod,even if i tagged it to belong to the playlist it wont list in the playlist.

if i try to synch it to the ipod in itunes, i will surely lose all my files,so how do i update the playlist of a manually synched ipod?