A few years ago, we could easily rely on a large collection of existing blog entries or educational articles to rank you higher than newer websites with less information; but that just doesn't seem to be the case anymore.
To maintain more stable ranking, you really do need to keep adding new information and even update the same few pages on your website often, like your home page, events, and special offers. An easy page to update monthly is your "birthstone of the month" page, just be creative and tell people about popular birthstone jewelry and how to match it with clothing fashions.
Google uses a very fast method to check the last update time of one of your web pages. It does this instead of spending the time to re-read your whole page. If they find a new page timestamp they send the Google spider to fetch the page.
The expression "youth is wasted on the young" is one we simply don't understand fully until we're up in years ourselves. It seems Google now has an affinity to rank younger web pages rather than the previous methodology that more closely resembled the expression "with age comes wisdom."
Each time you update one of your existing web pages, you have a fighting chance to compete with the younger website from your local competitor.
Routine updates can be the fountain of youth for your website. Keep dipping into the Fountain of SERP Ranking Youth.