Retain fields after submit

How do I retain fields after submit?

already tried this but no luck
<script>
document.addEventListener( ‘wpcf7mailsent’, function( event ) {
jQuery(‘.wpcf7’).find(‘form’)[0].reset();
}, false );
</script>

and I don’t want to edit the plugin like this
https://wordpress.org/support/topic/how-to-not-clear-or-autofill-certain-fields-after-submission/
because it will be erased on update

I’ve searched google and stackoverflow no luck.