How do I rewrite posttype "portfolio" to "program"

I want to rewrite the post type “portfolio” to “program” but If I change the name “portfolio” to “program”. The theme doesn’t work with it’s settings. So how do I rewrite it to work?

class Portfolio extends PostTypeAbstract
{
    protected $name = 'portfolio';
    protected $supports = array( 'title', 'editor', 'thumbnail' );

    protected function setLabels()
    {
        $this->labels = array(
            'menu_name'          => Translate::translate('Portfolio'),
            'name'               => Translate::translate('Portfolio Projects'),
            'name_admin_bar'     => Translate::translate('Portfolio'),
            'all_items'          => Translate::translate('All Portfolio')
        );
    }

Thanks!