Hi K.,
My 16 mo old is the same way, has to have it to sleep, but other than that she does not need it. I have to ask...are you weaning him because you want to or you are being pressured to? Don't just let him cry it out...maybe when he is 5 or 6 and it is damaging his teeth and he is old enough to understand that he has to give it up. His pacifier is still pacifying something and he needs it and uses it in the place of fearing something. I personally have not decided when the right time to wean mine off of it is, but here are a couple of suggestions I have heard of that worked...
My cousin called on the "Fy Fairy", she had a girl. Her "fy" would fall between the wall and the bed sometimes and once she could not find it, so she made up a story about a "FY Fairy" that would someday come and take her fy to a new baby who needed it. In the morning they did find it, but every time she could not find it Sarah would tell her about the "FY Fairy" and how she would come to visit little kids who were growing older and if she thought they were ready, and big girls and boys, then she would take their Fy's and give them to new babies that were little and needed them like she did when she was a baby. When ever Paige sees a baby with a Fy she talks about the Fairy and says that may be her old fi. Now, about five months later, she hardly even notices another pacifier.
The other trick I know of someone doing is cutting a whole in it. Slowly and very gradually she cut a tiny whole in the tip of the paci. One day her son brought it to her and said "Boken, it boken mommy," And she agreed that it was broken and that he had worn it out, "It was all done." On that note he took it over to the trash and said garbage and they threw it away together. I like this way because the child then sees what happens to it and knows where it went.