How to solve Google v3 reCaptcha timeout?

We've been running into this recently, too. I found this solution on GitHub and it's been working well for us.

This has the benefit of only asking for a token when the user interacts with the page (such as submitting a form) instead of having to keep asking for one.

<script>
  grecaptcha.ready(function() {
      document.getElementById('contactform').addEventListener("submit", function(event) {

        event.preventDefault();

        grecaptcha.execute('mykey', {action: 'homepage'}).then(function(token) {
           document.getElementById("googletoken").value = token; 
           document.getElementById('contactform').submit();
        });        
      }, false);

  });
</script>

If you do not wish to change your code too much then an alternative approach would be to wrap the reCaptcha JavaScript in a named function, set up an interval and poll that function prompting reCaptcha to add a new token to your form element 10 seconds before each two minute token expiry:

function getReCaptcha(){
    grecaptcha.ready(function() {
       ...
     });
 }

 getReCaptcha();  // This is the initial call
 setInterval(function(){getReCaptcha();}, 110000);