Change “Add to cart” text

How do i change the “Add to cart” text when using Ajax Add To Cart setting?
I saw another topic asking the same question, and the answer was to change the plugin code, which is totally against WordPress “best practice” and in general a very stupid thing to do.
If i update the plugin the text will revert to the default one from the plugin.
Could you please add the string as a filter that can be changed by the theme functions like every other WP plugin?

Would be awesome.