How to let Jupyterhub update letsencrypt certificates without stop-start ?

[sylvaticus]

On a Ubuntu 16.04 server I installed Jupyterhub and set it to use the letsencrypt generated certificates:

nano jupyterhub_config.py
c.JupyterHub.logo_file = '/var/www/nancy/imgs/jupyter-lef-logo.png'
c.JupyterHub.ssl_cert = '/etc/letsencrypt/live/nancy.org/fullchain.pem'
c.JupyterHub.ssl_key = '/etc/letsencrypt/live/nancy.org/privkey.pem'

The problem is that letsencrypt renews the certificates for a pretty short period (3 months), so I need to stop and restart Jupyterhub to update the certificates.

Is there a way other than start-stopping it to make jupyterhub aware of the new certificates?

(crosspost my old -and unanswered- question on s.o.: https://stackoverflow.com/questions/52443242 )