auto_br_admin.py

class AutoBrAdmin(admin.ModelAdmin):
    br_attrs = tuple()

    def get_object(self, request, object_id):
        obj = super(AutoBrAdmin, self).get_object(request, object_id)
        for attr in self.br_attrs:
            value = getattr(obj, attr)
            setattr(obj, attr, value.replace('\r\n', '').replace('<br>', '\r\n'))
        return obj

    def save_model(self, request, obj, form, change):
        for attr in self.br_attrs:
            value = getattr(obj, attr)
            setattr(obj, attr, value.replace('\r\n', '<br>'))
        super(AutoBrAdmin, self).save_model(request, obj, form, change)