That's a good question!
This is a very good question. And the answer is simple: yes.
Why? Because some of your articles are probably outdated and others need to be updated. On a blog, you always have to make sure you are up to date. Otherwise, your readers will end up sulking.
I clean up from time to time. I even prefer to delete an old article and make a new one instead of updating. But everyone does it as he feels.