Refresh the Captcha

Is there any way that a user can refresh the Captcha? I have a couple of forms that require the user to correctly fill in the captcha before submitting data.

During testing, I've on occasion had to either guess 4-5 times, substituting 0 for O, I for l, Z for 2 (you know what I mean), and have a few times had to resort to resetting the entire form and adding all the information in a second time, hoping the new captcha will be more obvious.

Am I missing the tool that ZOHO provides to accomplish this? Is there a way I can do it via code?

A small refresh/renew button to present the user with a new captcha is an absolute necessity.

Thanks for any suggestions!