As you can see from this Contact Form, I would want it that I will be able to place a text above the form in cases when the email and captcha is left blank or when the captcha is wrong, can I do it without using another HTML file?

Following the sample here it looks possible with

PHP Code:
header("Location:".$_SERVER['HTTP_REFERER']."?subject=$subject&from=$from&message=$message&wrong_code=true"); 
but I would like to be able to reset it, that is remove that div everytime the form is posted.

TIA