So there were some posts about this in the past, and I can't seem to find any of them.
I remember it being said that it would be looked into if additional add-ons could be added to a pledge. However, this still is not possible.
I could not afford everything I wanted up front, but now have no way of buying new stuff because I am locked out. Just because I couldn't afford them right away, shouldn't mean I shouldn't get access to them. I'm still a KickStarter Backer, just like the people who did happen to have all the money up front to buy what they wanted when they secured their pledge in the management area.
Without buying another copy, I can't get access to the AddOns again.
Was this definitely denied, or is this something that is still being contemplated?