Upgrading backing after the $900k goal.

So I'm fairly unfamiliar with the technical details of KickStarter, so I'm just going to ask this as a question here:

Say I back $50, then in two months or so decide that I really want a shirt and book of artwork, is it possible to upgrade from one tier of backing to a higher one?

You can upgrade as long as the kickstarter campaign itself runs. Thats usely 30 days. Your money will be transfered when the campaign ends and it it has reached it set goal.

If you want to get on a higher tier after the kickstarter campaign is over, i guess you will have to talk with the Company itself, if its okay for them. Except for the costum-support level that would be needed, i dont see a reason why the company should say no if you write them that you backed the game with this and this nickname/email at Kickstarter and want to get on a higher level.

In the end they still get more money. It could only be a issue if they had send out allrdy the production orders for the bonus items and fan-stuff.