I don't believe your personal documents are available in "Manage your Kindle". But I was thinking about it... I think you could use a 3rd party to keep track of your documents, and have them available to be re-sent if you delete them from the Kindle and then want them back. Dropbox is one way, and I see here's someone who illustrated how they used Dropbox to do that:
http://arthurpenskyfile.blogspot.com...-transfer.html
You could also... (if you have a internet connection that supports this, not everyone does)... but I could see using Calibre. and making your calibre library available for network connectivity (with a password, likely). and opening up that port. Presuming you have a static IP (which is usually extra to pay for, from your ISP). Anyway, it could be done. But it might cost you time and money. Dropbox, although a little more cumbersome, would work as well I think.