// Add each line item to the table.
foreach (element_children($form['line_items']) as $line_item_id) {
  $row = array(
    drupal_render($form['line_items'][$line_item_id]['remove']),
    drupal_render($form['line_items'][$line_item_id]['title']),
    drupal_render($form['line_items'][$line_item_id]['length']),
    drupal_render($form['line_items'][$line_item_id]['line_item_label']),
    drupal_render($form['line_items'][$line_item_id]['commerce_unit_price']),
    drupal_render($form['line_items'][$line_item_id]['quantity']),
    drupal_render($form['line_items'][$line_item_id]['commerce_total']),
  );

  $rows[] = $row;
}