You mean you want to change the foerground color?
I guess to do it properly you should include a check to see if the value is 100 yet and decide what to do then.
// 2013, use it at your own risk;
#target photoshop
if (app.documents.length > 0) {
var foreground = app.foregroundColor;
var theColor = new SolidColor;
theColor.hsb.hue = foreground.hsb.hue;
theColor.hsb.saturation = foreground.hsb.saturation + 3;
theColor.hsb.brightness = foreground.hsb.brightness;
app.foregroundColor = theColor;
};