It is easy to become obsessed with the PageRank of your website. Many people see it as the golden standard of how Google ranks your site against your competitors. It's best not to become obsessed with this because even if you have a high PageRank, another website can outrank you in the search engine results, even if they have a lower PageRank. Check your PageRank once in a while, but don't obsess over it because there are so many other things that you need to be focused on if you want to show up at the top of the search engines.
While you may not have a blog on your website that is updated daily, you can always update your site routinely by removing outdated information or fixing broken links. Every time you do this, it notifies the search engines to re-index your site for updates. Keeping your site relevant and up-to-date is very important for preserving page rank.