How do you create your Blog ?
Some places have you send XML or SOAP data, while some you just post text and
it does the rest.

So if you're sending text, I'd keep a copy of what you send maybe in a
separate text file with the date.

In other words make copies of whatever you send or post. That's the key to
your blog. You might be able to reconstruct a dead blog from HTML files. Try
it on one and see what's involved.