How to change color of watercolor brush art after clipping mask is made?

My first foray into watercolor brushes and clipping mask. 
I'm creating a set of the files in CMYK as well as RGB but this particular blue I'm using turns to a much different blue when converted to CMYK. To remedy, I'm having to go in and select a new CMYK blue that more closely matches the RGB. 

I can't seem to access the blue of the watercolor to change it. I've tried regrouping then releasing the clipping mask then selecting the new blue color swatch but it either colors it in the wild outline pattern of the watercolor or fills it solid. 

To complicate matters, I touched up a few white spots that needed a bit more fill color, in slightly different brush but on the same layer, if that makes a difference. 

Any help much appreciated! 🙂