Change the post URL

I am using the Valerie WordPress theme from Themeforest.

The code below is how it sets the URL for portfolio items:

register_post_type( 'project_post',
			array(
				'labels' => array(
					'name' => __( "Projects","um_lang"),
					'singular_name' => __( "Project" ,"um_lang")
				),
				'public' => true,
				'has_archive' => true,
				'rewrite' => array('slug' => "project_item", 'with_front' => TRUE),
				'supports' => array('title','editor','thumbnail','page-attributes')
			)
		);

I need, instead of “project_item”, for it to get the category for which the portfolio post is in. The current URL reads http://”siteurl”.com/project_item/”project_name”. How can I do this?