[Django]-Schemamigration/refactor model using south

if no changes in database, then you can create empty migrations for both apps in which was this model and which now has this model:

./manage.py schemamigration app1 del_model1 --empty
./manage.py schemamigration app2 add_model1 --empty

south analyze models which described in last migration and on this data he create next migrations