you should try build some natural backlinks from hight pr sites , with your unique articles . you can buy pr6+ links .
Many people are using this business "SeoRankMaster" (just type it on google) to increse pagerank, i never tried it but a friend of mine has tested it and it worked to increase from pr1 to pr2 =p hehe
I don't care about PR but I really care about Back Link. Why? because I have a blog PR3 but there is no visitor and other blog have no PR but have good visitors because this blog have many Back Link. That's True!
lol.. I have about 4,250,000 links (yahoo site ex) and about 120k a day, PR 4 site in the XXX genre making about 8K a month , took 4 years to achieve - though worth the effort!!~ ROOFIS
Bro, in my true opinion, Page Rank does not have any effect on how much money you are making with your website. And to answer you, you need 100s of website to increase your page rank from 5 to 6
I think you might want to keep on building dofollow backlinks from higher PR sources and keep your page contents update to date. Happy holiday,