Yes you can modify / reschedule your trip and you may be subject to a $50 fee. And the pricing, and Terms and Condition for your new date will apply.
Maybe a $50 fee plus the new pricing will apply and any discounts that you have will likely no longer apply. Here is the relevant portion of the Terms and Conditions:
Change Fees and Changes to Reservations Made Prior to Guest Arrival
- Changes to Reservation – Changes to reservation, including but not limited to change in travel dates, length of stay, party size or hotel accommodations, are subject to availability and the prices applicable at the time the change is requested and guest is responsible for paying any increase in price resulting from the change. In addition, changes made 30 days or less prior to guest arrival are also subject to a change fee of $50 per package plus any change fees assessed by third party hotels or other suppliers.
- If changes are made to the package including, but not limited to, changes to travel dates, package is subject to the Terms and Conditions applicable to packages at the time the change to the reservation is made and, in the case of changes to travel dates, pricing applicable to the new travel dates.
Dave