Note! There is now a native theme option in Shoptimizer since version 2.6.6 so this plugin is no longer required. Go to: Appearance > Customize > Layout > WooCommerce and enable Ajax update cart page quantity
A nice usability feature which really should be part of core WooCommerce is the ability to update the cart page when the quantity is changed. This would remove the need for a separate ‘update’ button and the page wouldn’t need to complete a refresh.
Fortunately, there is a plugin available which does just that called Ajax Cart AutoUpdate for WooCommerce.
Follow the instructions to install it and it should just work.