Perks to booking a future cruise while onboard?

[Ken at the beach]

5 minutes ago, jencruzin said:

But hold back on that last payment you may have, because it gives you more negotiating power to do the price checks - where they'll lock you in on current rates if they're lower, and take it off from your existing balance.

it gives you no more negotiating power.

 

As long as you are before Royals final payment date you can get the price drop whether the cruise is paid in full or not.  The only difference is if you had paid in full you will get a refund vs paying the lower amount