Ability Editor -> Shaman -> Restoration PvP
Find Frost Shawk.
Find this line of code (it's near the bottom) "and IsSpellInRange("Primal Strike", "target") == 1"
Replace it with "and PQR_UnitDistance("player", "target") > 20" -> that means it will cast it when you are more then 20 yards away from the target. You can change it to 30 or however many you want
Should work