DEFINITELY. Just go to "Manage your pledge," then under "Change your pledge" add the amount for the following incentives:
EXTRA BOOK - $20
EXTRA BUTTON SET - $10
EXTRA STICKER SET - $15
EXTRA SET OF POSTERS - $50
Add as much as you'd like! (Get 10,000 books if you want! THIS IS STRONGLY ENCOURAGED.) We'll sort out exactly which items you added when we send out our surveys at the end of the campaign.
What we can't get you, unfortunately, is multiple copies of the app. I'm not the technical one in the family, but I believe this is because of a witch's curse.