Well, it's what you'd do if for instance it was a NF (ie awake, not everyone does a DF when baby is asleep remember) and you got down to 1 or 2oz or even down to water only, then it would be a matter of helping get rid of an habitual NW.
The DF might actually be disturbing her sleep. If you pick her up to DF each night at the same time she might be rousing from her sleep and in effect you are teaching an habitual wake up. I just think if it's come to the point where the feed is bothering her you can drop now to zero, do a W2S and see how it pans out.