The process of replacing the file takes some time because it is a technically complex process. You should wait for at least 15 minutes for the changes to reflect. If even after 30 minutes you are unable to see the updated file, please clear your browser's cache and try again.  This waiting period applies to both on SlideShare and when your presentations are embedded on external blogs.

If you are continuing to see the old file, try opening the presentation URL in a new browser.  Sometimes the browser cache causes the old file to appear for a while, even though the replacement was successful.