Rebind a .mpp Project File to the new Team Foundation Server

See the following URL for instructions on how to rebind a .mpp file to a new TFS Server.
https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=273633&SiteID=1
You essentially right click the project and remove any properties on the Custom tab that begin with "VS Team System Data".  This will allow the bar in MS Project to enable the Choose Project button which you can use to connect to the new instance of TFS.