Ok... So I am changing a lot of my post on my wordpress blog to make them my SEO friendly. Some of the post are pretty old and havent been cached in a while. How can I get google to "check" and "update" these post again?
Consider resubmitting an XML sitemap to the major search engines and add the XML link to your robots.txt (example) file. Then link build like crazy. You should be re-indexed in no time. (Google Webmasters Tools is where you want to start w/ Google) Check out PingShot by FeedBurner if you haven't already for your WordPress blog. I find it helps content get indexed faster on new sites, so there is no reason it should help older sites too. Article marketing can help too (shameless self promotion time!) Free Article Marketing Videos Edit: Don't forget to 301 the old content!
If you are just editing some content there are no redirects involved, but if you are altering the URL's I would recommend 301 redirecting the old URL's to the new URL's Do any of your old pages have inbound links from other websites? Even though PageRank doesn't get passed through a 301 redirect it lets search engines know to find the content elsewhere (faster updating of new and old links) and it ensures visitors can still find the new content. If you are using something like the "All in one SEO pack" I believe it will take care of the redirects for you. (don't quote me on that though. )
Oh man, lol I'm sorry. I read "Post Structure" as "Directory Structure" for some reason. Lol You can pretty much ignore everything I said if the link's aren't changing I would just stick to link building and sitemap resubmission in this case.
Resubmit site map and if you didn't submit your old articles in top social sites than submit them this time . By this bots can visit these stories again .
If you are only doing changes in the content, then I guess you need to do nothing. Google will find out itself. However, you can build some backlinks for the internal pages, this will help in crawling those pages.