Increase the limit on the number of attachments per web form

While enhancing a web form, I reached the limit of the number of attachments a form can have: 15.

I know that when the form is filled, there will not be 15 attachments.  The developers need to change the limit to 30 or more.  I have a few places in the form with check boxes.  If you check a box, the person filling out the form needs to attach a document.  A description of the desired document is necessary.  

With this limiting factor, I will have to choose which options will have an attachment field.