Renaming a Django app that has migrations already sucks. This Is a way I found to do it that preserves your old migration history and keeps your contenttypes in order. The trick is, this migration cannot be in the app you are migrating, so stick it in your "core" app or another app you have installed. Just plug in your own old and new app names.

rename_table_migration.py

# -*- coding: utf-8 -*-

import datetime
from south.db import db
from south.v2 import SchemaMigration
from django.db import models
from django.db.models import get_app, get_models


class Migration(SchemaMigration):

    # old_name => new_name
    apps_to_rename = {
        'some_old_app' : 'some_new_app',
        'another_old_app' : 'another_new_app'
    }

    def forwards(self, orm):

        for old_appname, new_appname in self.apps_to_rename.items():

            # Renaming model from 'Foo' to 'Bar'                  
            db.execute("UPDATE south_migrationhistory SET app_name = %s WHERE app_name = %s", [new_appname, old_appname])                                                                                                    
            db.execute("UPDATE django_content_type SET app_label = %s WHERE app_label = %s", [new_appname, old_appname])                                                                                                    
            
            app = get_app(new_appname)
            for model in get_models(app, include_auto_created=True):
                if model._meta.proxy == True:
                    continue

                new_table_name = model._meta.db_table
                old_table_name = old_appname + new_table_name[len(new_appname):] 
            
                db.rename_table(old_table_name, new_table_name)                                                                                                                        
        

    def backwards(self, orm):

        for old_appname, new_appname in self.apps_to_rename.items():
            # Renaming model from 'Foo' to 'Bar'                  
            db.execute("UPDATE south_migrationhistory SET app_name = %s WHERE app_name = %s", [old_appname, new_appname])                                                                                                    
            db.execute("UPDATE django_content_type SET app_label = %s WHERE app_label = %s", [old_appname, new_appname])                                                                                                    
            
            app = get_app(new_appname)
            for model in get_models(app, include_auto_created=True):
                if model._meta.proxy == True:
                    continue
                    
                old_table_name = model._meta.db_table
                new_table_name = old_appname + old_table_name[len(new_appname):] 
            
                db.rename_table(old_table_name, new_table_name)