Sharepoint Automatipon-DocumentUpdate

Question

Hi,

 

I've implemented InfoPath form (More than one view). and successfully published on SharePoint Document Library. i have some data actually which imported in SP from Excel. specific document recognise using unique column which is "Application ID".

 

If it is new "Application ID" which means ID is not exist in Document library after submitting form data save in Library using SPD workflow.

 

Till now all are working fine. but in final moment i stuck here- If user enter "Application ID" which already exist in document library. after submitting form how data (.xml File) updated without loosing old data (.xml file).

 

Thanks