How to add a button or link to perform an action on a node with node_view?
You can implement the hook_node_view() like the following code:

function YOUR_MODULE_node_view($node, $view_mode, $langcode) {
  if ($node-&gt;type == 'CONTENT_TYPE_NAME') {
    $form = drupal_get_form('redirect_button_form');
    $node-&gt;content['redirect_button'] = $form;
 }
}

function redirect_button_form($form, &amp;$form_submit) {
    $form['submit'] = array(
        '#type' =&gt; 'submit',
        '#value' =&gt; t('New Item'),
    );
    return $form;
}

function redirect_button_form_submit($form, &amp;$form_state) {
    //here the path where you need to go
    $path = 'node/add/CONTENT_TYPE_NAME';
    drupal_goto($path);
}