If you're using a constant pressure to dispense, there is no reason to worry, as the dissolved CO2 concentration will ultimately reach equilibrium based on the temperature of the beer and the dispensing pressure. Just let off pressure every few days, and set to 8-12 psi, based on your personal preference.
In the future, unless you are doing it specifically for the differences in flavor that can result with keg refermentation, it is much easier just to force carbonate. Just set the keg to 8-12 psi and it will carb in 7-10 days. Alternatively, you can set it to 30 psi and it will carb in a day or two.