How to take the music from my ipod and put it in my itunes library?

I accidentally deleted about 400 songs from my itunes library, and i could just restore them from the recycle bin but it would take forever to load them back on to itunes so is there a way that I can, rather than sync from itunes, sync from my ipod? So when I plug my ipod into the computer the songs from my ipod will go onto my itunes?