you should definitely try to revive the plant if possible... I don't know if my memory serves me correctly, but switching from 12/12 to 18/6 or 24/0 will put the plant into shock.. causing hermaphrodism (But I could be making that all up)

I've had some plants in very shitty condition, and they literally had ZERO perk to the leaves, they were flush with the stem... probably without water for about the same time... In a week or so with proper care I'm sure it can perk up. It's called weed for a reason...

But if time is not an issue, and you want the *best* results, then it would be most ideal to sprout a new bean, and start over... Then you know it won't be stressed... as long as your other half doesnt touch it!