Migrating to version 15.1 from version 15 should be straightforward.
Make sure you've entered into the bentoctl
Python virtual environment, if you've set one up:
source env/bin/activate
Then, install the latest requirements / module versions:
pip install -r requirements.txt
Run the following commands to pull the latest service images and restart services as needed:
./bentoctl.bash pull
./bentoctl.bash start