Yes you can! Simply go to the "My Pets" section within your account page. Scroll down to the bottom of the "My Pets" page and click "Reorder".  From there, you may switch to a subscription, delivered as often as you would like!

In addition to the convenience of having a subscription auto-shipped to you as often as you like, you will also receive a 33% discount on your first subscription order and a 10% discount on every on-going subscription-based order.