Making google re crawl pages from a website

[speedo]

I have some very old website, with 6-12 months +++ content. I updated some content, and added a few new pages. I resubmitted the sitemap.txt file to google.... and guess what, the new pages are up there, but the content from old pages aren't updated in google yet. What i can do?! Is there anyway to "ping google", so i can tell it "hey , i just changed content on this very old website?!" ?!

[abigailpoul]

When a user enters a query, our machines search the index pages that match and return the results, we considered the most relevant users. Relevance is more than 200 factors, one of which is for a specific web page PageRank. PageRank is imported from other pages on the assessment of the importance of linked pages. Simply.