We started to night wean around that age too, maybe a little earlier actually. We cosleep, so he would nurse to sleep sometime between 7:30 - 9, nurse again around midnight, then no nursing until 5 or 530. Obviously things like being sick & teething disrupted this routine. I found that I needed to make sure he had enough to eat at dinner, and sometimes some yogurt right before bed, as he was getting hungry. Also some nights he was thirsty. Around 18 months or so we dropped the midnight nurse. Now, at 19, almost 20 months, I'm finally getting him to accept cuddling (I've been asking if he wants to cuddle for months now). So I guess the keys for me were making sure he wasn't getting hungry, thirsty, or too hot/cold. It didn't happen quickly either... you didn't mention when you had started.
Also, did you see the advice from Dr Jay Gordan (Gorden?) Google that if not, very helpful.
Loving mama to Aden (8/5/2010) and DSD (15).
We found the Jay Gordan website helpful. We nightweaned ds at 15 months & aimed for no nursing between 12-5. The big things that helped us were 1. doing it when dh was off work & we were both prepared for some rough nights (which actually didn't really happen) 2. keeping a waterbottle in bed & offering that when he woke. He would generally not want the waterbottle at first but once he took it he would drink & then go right back to sleep. To this day he still gets very thirsty in the night.
Surviving sleep deprivation one day at a time with dd (Oct '11) & ds (Oct '08).