We will be manually doing tier upgrades for Kickstarter backers once we have imported the data from Kickstarter into our forums. At the moment we have no way of modifying that data without the potential for causing problems later down the line.
If you filled in the form, we will email you when the upgrades are available
The FAQ still says "Q: I want to upgrade my package
A: Simply log in to your Kickstarter account, go to backed projects, and click “Increase Pledge.” Our thanks for your additional support!" at least that's what I see on the page.