Generic DOT3 or DOT4 fluid from the parts store should be fine. Bocephus is right though, you shouldnt mix different types. Since yours is so new, id be willing to bet its got DOT4 fluid in it. I'd recommend completely flushing the brake system at least every 2 years, perhaps even every season. Brake fluid is hygroscopic, meaning it absorbs water. Left in there, that water will eventually rust through your lines as well as foul up the pistons in both your actuator master cylinder and the cylinders in the calipers.
A GREAT brake fluid is Castrol LMA (low moisture absorbtion formula) if you can find it. I gave up looking and just ordered it online b/c I HAVE to use it on my land rover defender.