How to add more fields to an existing form which respondents have filled already

How to add more fields to an existing form which respondents have filled already

Hi All, I recently created a form where I received over 100 entries. I need to create another form which is to be filled by the same audience except that this time I just need to get some additional information like their date of birth and wedding anniversary?  actually am just adding 3 new fields to the existing form. How do I get the users to fill the form without having the users re-enter their information again thanks for your support