How to display a newly created node (created using a form) in the view using ajax (without page reload)?
As mentioned by wwwWRX you should use the #ajax property for your submit button and with in your function make a few changes. Before that you would want to remove your view from the block because we would be putting that here using code. 

the submit button would become

$form['submit'] = array(
    '#id' =&gt; 'update-submit-button',
    '#type' =&gt; 'submit',
    '#default_value' =&gt; t('Share'),
    '#ajax' =&gt; array(
        'callback' =&gt; 'add_update_page_submit',
        'wrapper' =&gt; 'update-list',
        'method' =&gt; 'replace',
        'effect' =&gt; 'fade',
    ),
  ); 


Add one more element to your form of the type #markup like below

$form['update_list'] = array(
 '#prefix' =&gt; '&lt;div id="update-list"&gt;',
   '#suffix' =&gt; '&lt;/div&gt;',
  '#markup' =&gt; views_embed_view('views-machine-name','block_name', $arg);

);


you should replace views-machine-name with the actual machine name of the view and block_name with the name of the specific block in the view and $arg would be the argument passed to the view which can be left blank if you dont have one. 

with in the function you need to make a few changes towards the end. 

you need to get rid of $form_state['redirect'] = '&lt;front&gt;';

and add

return views_embed_view('views-machine-name','block_name', $arg);


That should do it.