In some cases, Rhino doesn’t update the 2Shapes toolbar, then we can do it manually!
Find the latest version of 2Shapes.rui, by default is C:\Program Files\2Shapes for Rhino\6.0
Copy 2Shapes.rui to C:\Users\YOUR USER\AppData\Roaming\McNeel\Rhinoceros\6.0\UI\Plug-ins
One Windows trick:
You can go directy to C:\Users\YOUR USER\AppData just typing %appdata% in explorer.
If you have any question, please let me know.