I probably didn't really work as hard on it as my other blogs, didn't get enough backlinks for that one, thanks for your replies!
You can make quality content. PR is based on quality and quantity of back links, you can build back links.
Keep building more backlinks to your site. Google is not updating Pr regularly.They do it once a while. Make sure that next time they update you will have enough number of backlinks to your site to have a PR.