You don't need to do a thing. Every time you hit a new level you'll automatically collect that badge and the gift will be sent in your next box or in some cases separately.
And you don't actually redeem the points in a 'frequent flyer' type fashion, you keep collecting them as you go. So they don't go down when you hit your next level and get sent your gift, they keep building up. Or even worse, reset on an annual basis. But you only get the gift for each level you pass once of course :)