I have everything for kingdom death, so my question is, with this new kick starter what pledge level do I need so that I don't get something I already have, but get everything I don't have?
The $777 level pledge is an update + all the new stuff. It's not available currently, but we'll see. If you go for the next one (777+150=$927) instead of the core game upgrade, you will get a full new core game.
ALternatively, get the $195 pledge and cherry pick every new thing that you like as addon.