I'd probably remove 1/3 of the whites and half of the royal blues. Remove the green/red if you don't want them for color balance, the 6500k whites should give enough of that spectrum.
Replacing the diodes with 5W is not going to do anything if the drivers that are in the fixture can't push more current. You didn't say you were replacing the drivers so putting 5W diodes won't do anything for you.