You can’t. Unfortunately, Slideshare removed the option of updating a file. So you can’t re-upload a file if you’ve made updates to your slides. If you want to “update” your current file you will have to delete it and upload the new one. This of course will remove all the stats you had in the previous file as the system will consider the new upload a new file.
Why would Slideshare do such a thing? Don’t ask me why, but here’s their explanation.
I find this really unfortunate and a major design oversight as you were able to easily update files in Slideshare without losing any of the stats prior to the acquisition from LinkedIn (oh yes, LinkedIn bought Slideshare in case you weren’t aware of that already).
So what’s my take on the whole thing? Well, probably some “genius” in LinkedIn thought this was a good idea. I’ll ask you a simple question for your reflection. In what planet in the Universe is updating a file not a typical every day use case? Obviously, the guy who made this decision should be sacked and they should re-instate the functionality.