Increase varchar field size (existing in the database) with NHibernate

Let's say that this field with size 11 exists in the database, across multiple clients.

Map(x => x.CpfCnpj).Not.Nullable().Length(11);

And one day I need to raise it to .Length (14). Is there any way to configure for NHibernate to do this automatically, or just via script in the database?

I suppose I have something here to configure, I just have not found it yet:

FluentConfiguration FConf = Fluently.Configure()
                .Database(configDB)
                .Mappings(c => c.FluentMappings.AddFromAssemblyOf<Map.UsuarioMap>())
                .ExposeConfiguration(cfg => new SchemaUpdate(cfg).Execute(false, true));