Do you want to get rid of Robert, or the whole lovey thing altogether? If Robert is the problem, could you maybe give him to Santa, as you say, and Santa brings a new 'big boy' lovey (would need to be something similar to Robert I would assume) - one that you can get 3 or 4 (or more) of so that the washing etc isn't such an issue. Maybe make a big thing of Santa bringing it for Stan as he's getting to be a big boy, and that this is his last year with a lovey or something, ie Santa will be taking this one next Christmas and that's it? So he can maybe begin to understand that at Christmas (next year) he'll have to part with a lovey altogether - giving him time to get used to the idea.
I don't know Anna, reading this through I'm not sure it's a good idea or not!