From their website
Best Price Guarantee
For sailings booked by March 31, 2022 that depart by September 30, 2022, our Best Price Guarantee gives you an adjustment if you spot a better price on your cruise. So you’re ensured to get the best value. Give us a call up to 48 hours before your sail date and you’ll receive the price difference as an onboard credit or rate adjustment — it’s your choice.