I am trying to update the model by right-clicking on the .edmx file and selecting "Update model in database". However this option is not available in the contextual menu... am I missing something?
When you open the .edmx file, the designer view opens.
When you press right mouse button there, you have the option "Update model from database".
Also the Model Browser window opens, you can also use the right mouse button there on any entity to 'update model from database'.