Personally, I'd keep riding it as-is until you get to the point where the 48 big ring isn't big enough (or you wear out the chainrings), then switch over to a road crankset. If you're not out of gears top or bottom, there's no need to change anything. Of course, I ride (among others) a bike with a 1x5 drivetrain in the undulating terrain around here, so maybe I'm not the best one to speak about fine-tuning gearing.