How Many Viewers Do You Have
Are your page views down over the past week, month or year? If views are down, it could be a sign that you need to get something different up on your blog. Try a new design, maybe add a comments section or maybe put your blog on a new domain. Think of ways that you can use SEO to make a difference for your blog.
Do Readers Connect With You
Maybe it is time to put some different types of content on your blog. Your opinions and observations might have been fresh and new when you first started the blog, but your readers might be looking for something more out of you. Perhaps the issues that you deal with aren't relevant, or maybe your opinion has been beat to death and you need to talk about something new.
What Is Your Opinion
Are you still having fun writing your blog? If you are not having fun, it will show in your writing. It will all start to sound the same and your readers will notice if you are mailing it in. Your writing should be a reflection of your voice. Pretend that you were talking to your audience face to face. If you cannot put the same passion into your writing as you would in a speech, it might be time to start to write about something else.
Is Your Blog Current
When you leave a blog alone for a time, and then come back to it, it is almost certainly time to give it on overhaul. Update the content, update your contact information and make it sound current. Doing anything else would defeat the purpose of writing a blog in the first place.
When does your blog need a facelift? It depends on whether or not you are still having fun writing your blog, or if it is woefully out of date. As long as your readers still read it, and still like it, it should be u to you as to whether you update it.