D7: copy data from node to node
I don't know if it's the best way to do it, but if I was in this situation I will do that way:
hook_form_alter => use a sql query to get the last node id of his last post, then node_load() and in form_alter copy the data you got from node_load() into the new node.

This solution should work if you already have a value in at least one of the previous one.

function YOURMODULENAME_form_alter(&amp;$form, &amp;$form_state, $form_id) {
    //get your form id of the admin activity page
    drupal_set_message($form_id); //or echo $form_id; it should be activity_node_form
    if($form_id == 'activity_node_form'){
        $form['#submit'][] = 'YOURMODULENAME_submit';
    }

}

function YOURMODULENAME_submit(&amp;$form, &amp;$form_state){
    if(isset($form_state['values']['field_activitiy'][LANGUAGE_NONE][0]['value'])){
        if(empty($form_state['values']['field_activitiy'][LANGUAGE_NONE][0]['value'])){
           $lastNode =  YOURMODULENAME_query();

           $node = node_load($lastNode['entity_id']);
           if(isset($node-&gt;field_activitiy[LANGUAGE_NONE][0]['value'])){
                $form_state['values']['field_activitiy'][LANGUAGE_NONE][0]['value'] = $node-&gt;field_activitiy[LANGUAGE_NONE][0]['value'];
           }
        }
    }
}

function YOURMODULENAME_query(){
    global $user;

    $query = db_select('node', 'n');
    $query-&gt;join('field_data_field_activity', 'a', 'n.nid = a.entity_id');
    $query-&gt;condition('n.uid',$user-&gt;uid,'=');
    $query-&gt;fields('a', array('entity_id'));
    $query-&gt;orderBy('a.entity_id', 'DESC');
    $query-&gt;range(0,1);
    $result = $query-&gt;execute()-&gt;fetchAssoc();
    return $result;
}


Tell me if you got an error.
PS:once you got the form_is remove the line

drupal_set_message($form_id);