Your site has a file just for the Search Engines. Yours is called http://www.richmentorship.com/sitemap.xml
When you build a page, the date that page was built is written into the file. It's called the <lastmod> date. All your images and other assets are also listed in that file.
Here's a picture of part of your own file with the lastmod dates highlighted.
When you build a page, SBI automatically sends that file to the Search Engines, without you doing anything. I "think" SBI submits changed sitemaps once a day. This is called "pinging the Search Engines".
That file gives them the address of your website, and they will then schedule a crawl of the site. Every time you build a new page, the change in the <lastmod> date in the file will signal that there's a new page to crawl. If you build pages regularly, then SBI ping the Search Engines regularly, letting them know there are new pages.
You can request a crawl yourself, by using Fetch and Render in the Google Search Console.
If, over time, you don't build many new pages, they won't come back very often. The engines only have finite resources and save them up for sites that change more often. Google does like to see websites that are continually updating content, that are alive and evolving.
From a Search Engine point of view, I don't think it matters if you put the date on the page or not. The lastmod date tells them what they want to know, and you can't change that.
From a human point of view, adding the date tells people reading that your site is active, and that the information is still timely. That might then influence how long they stay on the page.