If you have the carbonation correct at serving temperature, try chilling the kegs, counterflow equipment and bottles to near 32F then bottling. The CO2 in the beer is less likely to come out of solution, so you'll lose less in the process.
Or you can hit it with some more gas ahead of time to raise the level.
The problem with giving specific answers is that most people don't have the way to directly measure the result. So if I said "make it 0.5 volumes higher", would you have a way to measure that?
Do a test bottle and come back the next day and see if you like the results.
I might hit my keg with 30psi for 10 seconds, shaking, if I wanted to raise the carbonation a bit. Then let it sit cold overnight. Repeat until happy.
To lower carbonation, leave keg warm, then vent it. Shake keg a bit, let sit for awhile, then vent again (slowly). Repeat until happy.
This is something I do totally by taste.