rockshox seatpost bleed?

I bought and installed the seat post a month ago, seemed to be working fine without a tweak for the first few rides but now it wont return up unless i pull it back up while holding the button in. Ive adjusted the return speed to max but that hasnt helped.

Im assuming I need to do something with the fluid. It did come with a suringe and bottle of fluid. Do i add or remove fluid? Is this something i should get the LBS to do? I have no experiance with hydrolic repairs. If its as simple as screwing in the suringe and adding some fluid i think i could do that myself. But how much? The more fluid the faster the return?