If you know you're using the exact same clutch disk material and the flywheel is still flat and the machining is good (i.e., it's not burned and in very clean shape), you may not even need to have it resurfaced. This is fairly rare if the clutch wore out, but it may happen.
If the clutch disk is a different material than what was used before or you're not sure, or if there's any burning (discoloration) or scratches on the flywheel surface, get it blanchard ground (i.e., resurfaced).