Sure. Just add $25 to your normal pledge per additional standard kit. We'll do the math to figure it out for you. And you can also remind us when we send out the backer survey after the project ends.
Note 5/1/14: We just added new reward levels for quantities of two (2) and five (5) DELUXE kits, so if you want more than one DELUXE kit, it's best to switch rewards rather than simply increasing your pledge.