Totally! Just log in to My Account ---> Click "View/Make Changes" next to your ACTIVE subscription. Then click "Switch Subscription" to edit your flavors ---> and add/drop flavors from the fun little ingredient images. Hit "CHECKOUT" and make sure to submit the billing form and click your saved CC info at the bottom - this just updates your information, doesn't process a new order.
Here's a short how-to video: Change your Picky Club flavors and quantities