My mare foaled almost 3 years ago and she still drips milk on occasion. I kept waiting for her to "dry up" and in never really happened.
I did what everyone else says and just let her be "full" and gradually her body realizes she's not nursing anymore. My mare still drips now and then I think because she was a broodmare her whole life everything is really saggy and stretched out.
But anyway, yes, do stop milking or she will just keep making more.