I night-time weaned by refusing the bb, offering a drink of water instead and lots of cuddling in our bed. DD started the night in her own bed and would then come into us when she wanted me (and bbs generally). I had a few nights of an unhappy DD while I refused the bb, but it wasn't *that* bad and I was always with her while she was upset. I still bf her in the morning (I adopted the rule of 'bbs are asleep while it's dark, you have to wait until the sun comes up') and before bed-time, so she wasn't completely weaned.

I think if you're consistent he will get there. I should add that DD's increased night-time bfing came out of the blue at around 16 mths and wasn't something she had always done. I don't know if it was developmental or just a phase where she needed the comfort of me and bbs more, but it did pass.