For example: One article is already indexed in Google, and after 3 or 4 months I made some changes in the same article, adding a few links or some content. I want to know, will Google crawl the same article again and add the new links?
It affects the indexing. If google crawl that page again, It will renew the indexing which can be seen in cache. I am 70% sure that your page will index again.
Google engine is usually crawling to website/blog in the period of time. If it find some new updated contents or article, it will collect the latest one and store in its memory. The old data will stay as cache page, and then finally will suspend.
You have to remove 70% duplicate content from you article then it will indexed with new one because Google scan always for pre duplicate content.
Yes, Google update their index time to time, during this goggle index your article so that's why i am sure 80% your article will be crawl by Google. thanks for asking this.
