If you upload xml files to any server (for example the account I gave you at our server) and make link to the xml file.
You can upload xml file to the server and user will be able to download updated files.
If you really need it, I can try to modify the code so that:
File will be replaced when the same filename was attached.

I have been working on project related to open source. I do not need money from users. User can have better use of his/her own money. What I enjoy most are feedbacks/suggestions from users. :-)