Once tested positive for hsv2, does it mean it's an accurate result? or should a patient re-do the test again? if so, what's the time period to do it?

Accurate, but...: Lab tests are tested to determine their level of accuracy under certain circumstances. If a commonly done test is performed by a commercial lab, for the right circumstances, the result is accurate. One's doctor gets to decide if a test should be repeated (the doctor knows the actual circumstances for his patient), because "accurate" does not mean 100% accurate. Life is not 100% one way or another.