Most boards do not need sharpening regularly. In fact, unless you are racing, do not even worry about sharpening your edges. Instead think about it as shaping and deburring.
- Shaping occasionally with a file by a skilled hand.
- Deburring often with a stone.
Once I adopted this philosophy, my board became a lot easier to maintain. Remember, a board with "sharp" edges and with burrs is a LOT worse off than a board with "not so sharp" edges and no burrs. Also, sharp edges burr a lot easier.