My bad, I did not close the if statement. So here is the new code:
if($this->_config->tableCaption == 'Performance'){
$field['output_script'] .="<script>
setInterval(function(){
searchjx('".$this->ajaxURL("", "", 0 )."', '$this->_ID');
}, 10000);
</script>";
}
And one more thing. This will refresh table every 10 sec. if you want to change time interval just change the number 10000(this are ms) at the end of the code