You can make people leave servers however you can't make them join again they would have to join back there self
Without client mods or spout there is no way to make the player reconnect to the server. It is just like the server-to-server problem for transporter.
Just thinking about this, would http://dev.bukkit.org/server-mods/bungee-cord/ work?
Not sure how that whole thing works but it would be way too much work for such a small command I would expect no one to be willing to.
