Why did you take it away? Was she waking for it?
My DD#2 was similar, in her case she WAS waking when it came out, but once she was able to re-plug on her own, we just bought her some extras. She gave it up on her own around 2.5YO for most of the day, took another couple months to get rid of it for sleep. She just had a REALLY REALLY strong need to suck, and a need for comfort. I still remember keeping a spare in my right-side pants pocket at all times from about 2-2/5YO for her.
If there isn't a real reason for her NOT to have it, I'd consider letting her have it back, at least for sleep times.