Here is how to update WhatsApp:
You can also check for updates manually at http://www.whatsapp.com/download.
The process of updating WhatsApp will likely solve problems and may also include new features.
Remember that you do not need to remove or uninstall WhatsApp in order to update. If you do remove WhatsApp, you may lose your entire WhatsApp chat history. To learn more about chat history read this article.