Changed the name of django app.Now python manage.py shell cant see the models.
Editing the Answer. I misunderstood the question earlier
Hey, if the server is running and site is working as expected (as you mentioned) and you are facing problems only in shell, you just have to close the shell and reopen it.
However, here it seems that you have not added init.py file in the new folder as it can not fing models.py. If that is not the case, please edit the question to show the list of installed apps and the entire stack trace.
This is what I did to change the name of my django app which has classes under models
I deleted the database and the migration folder. Then I ran the migration again and the tables were created ( mariadb). All works fine. Except when I run 
python manage.py shell which starts the interpretor alright. But when I try to from main.models import Teacher I get a LookupError: No installed app with label 'models' . Teacher being the class under models.py of the app main. Main is what I had renamed my earlier app 'foo' to