Refreshing old content for your blog is a great thing especially when a niche is competitive. Old content is as useful as the new one, the only difference is age.
Usually, Google gives more priority to new content. If you wrote a post in 2015 and another person posts a similar one in 2020, the newest post has a better chance of ranking higher than your old post. Search engines assume that the new content has more information, hence more useful.
Old content will drop in rakings over time—this year, your popular article will be on page one of Google, if you search for it next year, you’re likely to find it on page 2 or 3. This happens because other bloggers are also creating similar content.
If you keep on neglecting the archived/old content, they will drop in rankings until you start getting zero organic traffic from them. The best idea is to dedicate some time to you go through old content, add some details and repost. You can even change dates to current—but don’t delete the content.
I experienced one thing with one of my blogs made me realize my mistakes. I never used to refresh my content. Every time I posted fresh articles, they ranked top, I assumed things would be straight as such. There was an article I posted in 2016, that article was always on page 1 of Google, it was given special priority. I never bothered to check how it performed. For two years, that single article attracted 400,000 visits.
Last year, I tried to search for the same article to see how it was fairing, to my surprise it had been thrown to page four. Other bloggers had realized that the content was performing well, they posted similar articles as mine and ranked better. I went ahead and edited it, adding fresh meat to it. After two days, it was pushed back to page one.
It’s important as a blogger to ensure that all the articles that bring organic traffic are refreshed from time to time.