Add to cart button missing

WordPress updated to 3.9 and now my Add to Cart button is missing for variable products. I’ve trawled through old threads on the topic and I’ve tried every fix I can find (disable all plug-ins, etc) but can’t get anything to work.

I have some js errors but I’m not sure what to do about them.

I’m really hoping someone can point me in the right direction.

http://www.sogniclothing.com/shop is the site.

Thanks

https://wordpress.org/plugins/woocommerce/