I'm all for taking the time to answer good questions with my own creative, well-written, entertaining, detailed, and carefully crafted responses 😉
But sometimes the answer is already online if you know where to look for it. Nothing I write will be better than that.
Unfortunately, sometimes those answers are not easy to find. In this case, Google does have instructions for what you need to do: https://support.google.com/webmasters/answer/6065812?hl=en
I have done what they describe, and the time it takes for them to take action seems to vary (and note their caveat that they don't guarantee to re-crawl every page of the site based on your request). I know that if you do NOTHING, the site will eventually get crawled again. Sounds like you're anxious to have them do it ASAP, so going this route can't do anything but make it happen faster than it might otherwise.
It sounds like you are talking about the act of pinging a site? A ping is like ringing a bell to whatever site to say HEY YO I made changes!!
Here is the link to google ping, http://googleping.org/
Read up on this practice, might help you in the future 🙂 Several sites offer this
Hope this helps