SEO drop in Traffic | Changed Year in Tittle

I am currently experiencing a 40% drop in traffic. No penalties in google console. I think it has to do with me changing 2 or 3 or the titles from Example:

Best Ultra Notebooks in 2018
to
Best Ultra Notebooks in 2019

I didn't change the URLs and only update a couple places in the content that said 2018. I was ranking for 2018 keywords and now my position has dropped almost 2 spots.

My question is how long will it take to get the traffic to bounce back? and also is there a smarter way to do this in the future to avoid and SEO issues.

Actually I'm quite confused on what to do. I'm ranking for 2018 but it's 2019 so i dont know if it would be a good idea to change them back cause its 2019. On the other hand if I change it back to 2018 the links to the products will be 404 and useless in a couple months. And if I make a new 2019 version I will have 2 articles almost exactly the same except for the year. I think that's keyword cannibalization even if I link the 2018 article to the 2019 article.

Please help!

There might be some change in google guidelines or any new update which hurts your ranking.Webmaster will help

Could be too the traffic itself is just lower? For that search term

Erin,
I clearly say there is no penality but since you have changed the URL, it is having impact on the ranking factor.
See, Tell you what, 2018 has gone, so you shouldn't think of 2018 but rather go for Best Ultra Notebooks in 2019.
I know you would have drop in ranking for a few days or weeks but in meantime you can add some link juice for this page then everything will be fine back like it was working or 2018.
Make sure, you changes the permalink as well, www.yoursite.com/Best-Ultra-Notebooks-in-2019/ (sometimes only title changes not the permalink)
Good luck buddy!!