I see you’re using the standard jupyter notebook UI. It’s possible to write a small JS extension that modifies the content of cells whenever the notebook is loaded, as described in the following thread:
https://github.com/jupyter/notebook/issues/1451
It’s also possible to do this in Jupyterlab, but it uses a differnet syntax for plugin definitions
As a simpler alternative, you can use the pre/post_save hooks in your jupyter_notebook_config.py to insert/modify cells before they’re written to disk. A downside of this is that the changes will only be visible after the notebook has been saved (and reloaded by the user) at least once