Yes! Just log in to your account and visit the "Autoship" section of your account. Then, next to "Ships" on the product you'd like to change, click on the link. In the popup, choose a new date by clicking on the calendar icon and then click submit. Your subscription will now renew on this new date.
Please note: If you need to change the frequency, you'll need to do this as well (by clicking on the frequency link as shown in the screenshot above). Changing the date will not update your frequency.