Do Uploaded documents save when a form is submitted?

We have created a lengthy form and have some spots for uploads.  When the form is submitted we have added a link so the user can return to the form to update or change information after submission.  Everything seems to save okay except the uploaded files.  It seems like we are losing those. 

Are the file uploads something that are saved when a user returns to a form or must they re-upload everytime?

Thank you

File uploads are retained when editing submissions, however, if multiple files are not allowed for the field, it will accept a new file for the field instead of adding more files in addition to the original: