Limit Form Submission

Hi

Is there a way for me to limit form submission to once only either by email address ( preferred ) or by IP on say si contact form 1 only.

I am looking to create a survey which when filled user would then have an option to select an offer from a dropdown, this is not a problem but I need to restrict the submission to once only.

Thanks

http://ww.wp.xz.cn/plugins/si-contact-form/