What brand and model brush do you use?  You might want to check with the manufacturer, too, for care and maintenance tips.

I've got a Paasche VL, and an Iwata Neo; both companies are pretty good with that kind of info, and also with service for replacement parts.

I do similar to Momo-I use water or isopropyl, after spraying water-based paints, mineral spirits with enamels, lacquer thinner with lacquers.  I will run SuperClean through, too, after water-based paints.  But I also do a field-strip and cleaning every so often, blowing lacquer thinner through, then water to flush it.  I've got a set of micro brushes to use for cleaning, too.