Question: If a particular page of my website is indexed at Google for a long time and If I changed the content or meta tags recently, how long does it takes Google to reindex or recrawl the page again and update the results?
In the following video, Google engineer Matt cutts shares some good tips regarding how often Google crawls and reindexes your webpage, if you change the content of the page after a long time.
According to Matt, Google will crawl your page at definite intervals and look if the page has updated or if it has “additional content”, since the last time the bots crawled and indexed that page. If after successive visits the bots find no new or “fresh” content, they may lower the frequency of crawling.
However, if you change the content of the page after a while, the bots will discover the change sooner or later and they will refresh their index. There is no need to update your sitemap or submit the page again in Google webmaster tools.
According to me, there is no need to worry about reindexing or recrawling, as the bots are smart enough to determine how often they should crawl a particular page of your blog. If your site structure is good and every page is accessible via static links, the bots will have no problem finding and crawling the particular page in question.