Resume function - retain Flash cookie when updating published file

I learned from this thread here that Storyline's 'Resume' function is enabled by a Flash cookie being stored in the user's browser. We've set up our courses to store a lot of information about user's progress and results within the course, and it's great that when they access it again on the same computer, it remembers everything they've done – Fantastic!

The problem we're having is that if/when we ever make a small update to the .story file and then republish the project (even though it has the same file name and is uploaded to the same web directory), unfortunately this resets everything and the user's progress data is lost. 

I understand that when we republish, it's effectively a whole new course. But it's a big issue when we just want to update a few words on one slide, and this means that all of our users' stored data will be lost.

So I'm wondering... Does anyone know the specifics of how Storyline sends the Flash cookie to the browser? Is there any way to perhaps overwrite some files in the published output to retain the Flash cookie 'code' from the originally published file?

I noticed that in the meta.xml file in the published output folder, there is a 'project id' number and a 'course id' number. The 'course id' seems to remain consistent whenever I republish a course from the same story file. But the 'project id' seems to be unique every time I click the Publish button (even if there were no changes made to the .story file). So I wondered if perhaps I could overwrite the 'project id' number of the new version with the number from the original version, so that it would remember the 'resume' data... But this didn't work unfortunately.

So, if anyone knows a little 'hack' for how we can trick the user's browser into thinking that it's the same file as before and therefore retain users' completion data, we would be very grateful! :)