If you changed the price, there will be a warning in the order that the price has changed.
An order displays the prices at which the reservation was initially made.
To refresh the calculated price, click on Edit button of the reservation.
And then, click Save.
After saving, the new price is displayed in the Calculated section.
The warning disappeared.
But the Final invoice still displays the initial price with a blue warning.
This way you can compare prices.
You can also Update the final invoice.
Then all warnings will disappear and the total amount will be calculated according to the new prices.