I wouldn't worry about it. Page rank has been pretty much irrelevant for quite a while and it's probably never going to be updated. See this for example on searchengineland.com
Google Toolbar PageRank Finally & Officially Dead?

Suggest put your efforts in to gaining traffic and visitors. Time better spent.

Page rank might not be relevant anymore but it does give you some authority status among other sites online so I understand why you want a high PR.

Simply get a few High PR backlinks from other authority sites and yours will increase. The easiest way I know how, is to simply do a Google search for your niche. Something like this:

"keyword" resources
"keyword" links
intitle:"keyword" resources
intitle:"keyword" links
"keyword" recommended resources

There's a lot of different search strings you can use. Simply find those sites then build a relationship with the site owner and later ask them to link to your site. No need for loopholes or doing anything dodgy, you'll get a legit authority link.

Look for resource pages that have very high page rank don't go for anything with PR2 or less. You don't need to contact 100's of people, you can be smart and simply get 2 PR5 backlinks. You can buy the links if you want to, but I would rather bribe the website owner who I already have a good relationship with.

Hope that helps.

Try Moz's domain authority. It's more up to date. PR won't be updated for the same reason Google hides organic search keyword info.

Pagerank is just not going to made public (via toolbar) anymore. Its not gone completely.

You could blog for 10 more. Content doesn't get you higher PR people linking to you does. If no one links to you you are still stuck

However as others have stated you may never see an increase since pagerank might never be publicly updated again. concentrate on whats more important anyway - rankings

The Domain Authority and Page Authority from opensiteexplorer.org is a better measure of how a blog is performing in terms of authority than a PR

Pagerank is no longer being updated so forget about it and focus on improving your traffic. If you really want a higher PR, build 100 high PR do-follow blog comment backlinks and during the next PR update you'll get a minimum of PR 3, if it ever gets updated again.

You'll get better success using this trick

1) Find a hot topic using buzzsumo or similar tools related to your article
2) Tweak your article to reflect some of that hot buzz that influential people in your niche are excited about
3) Use buzzsumo or topsy to find people who shared similar content
4) reach out to those people via social media
5) Encourage them to share your stuff

Many of these influential people have bloggers following them and you can get backlinks this way without resorting to guest posting

For whitehat SEO, the rules have changed. SEO outreach is the name of the game. Use social media to build influence with the right people so you can benefit in terms of earned links.