Just because you've launched your blogsite doesn't mean the hard work is over. You don't want to create a negative impression of your site or your business by having broken links, outdated information or irrelevant content. Check your blog site regularly and make the appropriate updates.
LOL. I think broken links, outdated information or irrelevant content are the surefire ways of knowing whether or not a certain blog is being neglected. I shamefully admit, that some of MY blogs are being neglected... I just get bored too quickly and stop updating them for some reason!
I suppose it gets hard sometimes to keep making that effort on your blog! But it usually pays off if you really want to.