No, the ‘Have it All Early Booking Bonus’ cannot be purchased while you are on board the ship.
Because the ‘Early Booking Bonus’ is offered for a limited time, the opportunity to purchase it ends before your cruise departure date. It will not be available to add during your sailing.
That said, once that limited-time window has expired, you can still choose to purchase the ‘Have It All' package (either pre-cruise or after departure). This means you still have a simple way to add popular amenities, even if your vacation is already underway.