Hi,
I think Mohamed overlooked the fact that you're using the new add to cart system and not the legacy one.
The checkout/notice.php view file is only used with the legacy add to cart system so changing something there won't help in your case.
You would have to edit the line:
{text:"'.JText::_('CONTINUE_SHOPPING', true).'",type:"submit",className:"vex-dialog-button-primary",click:function continueClick(){}}
and change it to something like:
{text:"'.JText::_('CONTINUE_SHOPPING', true).'",type:"submit",className:"vex-dialog-button-primary",click:function proceedClick(){window.location="XXX";}}
in the file plugins/hikashop/cartnotify/cartnotify.php where XXX is the URL that you want when you click on the "continue shopping" button.