yii2 refresh captcha when validation fails -

i using default captcha widget advanced yii2 template.i want refresh captcha image if validation fails.i tried trigger mentioned in previous trails,but want refresh image whenever captcha fails.

<?= $form->field($model, 'captcha')->widget(captcha::classname(), [ 'template' => '{image} <a href="javascript:;" onclick="captchref()" >refresh</a>{input}', ])?>  <script>     function captchref(){          $("img[id$='-captcha-image']").trigger('click');     }      $(document).ready(function(){          jquery.ajax({              'success': function(html){                 jquery("#yw0").attr("src",html)             },              'url':'captcha?refresh=1',              'cache':false          });          return false;      }); </script> 

have tried using testlimit. can set testlimit value 1.