Cast Improved Invis. Even if the Deepwood Sniper has see invis or similar magics, the range on those effects will probably be short enough the DS has to move into your Blindsight range to target you. Also, Protection from Arrows will knock 10 points off all the DS's shots.
Something like teleporting to your lair, casting Greater Scrying, buffing up like crazy, and then teleporting 10 ft away from the poor DS might work too. However, it's a bit risky as the DS could be the bait in an ambush. If the dragon has a contingency, then go for it. With haste, the teleport is free partial, then the full attack goes off. With full buffs and power attack, the dragon can probably eat the DS in a round. If the DS doesn't look like it's going to drop on the last attack, have the dragon use its last shot in the round to Sunder the bow.