There should be an “Update” button shown in the extension manager. But there is no notification right now, you may wish to open an feature request issue on JupyterLab repo.
- Can the Extension Manager install a newer version of the extension directly, or does the user need to uninstall the existing extension and install it again to get the latest? My tests were not conclusive.
Yes, it can; if it does not work, please open a detailed bug report with all the infromation needed to reproduce (Issues · jupyterlab/jupyterlab · GitHub).