Originally Posted by Illuveatar
I once used a 25 year old yeast packet I found in my step dads garage.
Felt the need to point out that the OP is using white labs sweet mead yeast, which is liquid yeast. 25 year old liquid yeast would be no good, I think. So yeah, OP, understand he was talking about dry yeast and not the liquid yeast you're using.
OP - definitely throw in some nutrients and stir it around. If you didn't add any at the beginning, throw in a full dose (if you did, do like a half or 3/4 dose). I've had lots of success after the 1/3 mark people have mentioned. LD Carlson has a great yeast nutrient/energizer that I've specifically used in conjunction with WLP720 to get it going again once it started slowing down, but you could really use most any yeast nutrient. The sooner you get it in there and stir it around, the better.
EDIT - saw the OP had answered one of my questions earlier in the thread, so I deleted it.