Refreshing beats publishing, most of the time
The default answer to "we need more organic traffic" is to publish more. It is usually the more expensive path to the same place.
A new page starts with nothing: no history, no links, no established relevance. It has to earn its way from invisible to page two before it earns anything at all, and most never make it.
A page ranking at position 12 has already done all of that. It is one improvement away from meaningful traffic.
Choosing what to refresh
Pull queries with meaningful impressions and average position between roughly 8 and 20. Group them by the page that receives them. Rank by impressions.
The top of that list is your refresh queue, and it is ordered by opportunity rather than by whichever page someone remembers.
What a refresh actually involves
Not rewriting the page. Usually four smaller things:
Cover the questions the page nearly answers. Its query list tells you what people expected to find. If a page ranks for six phrasings and properly addresses three, add the other three.
Fix the title and heading. Put the phrase people search in the first few words, and make the H1 agree with the title.
Add internal links to it, from pages that already have authority, with anchor text describing it.
Update anything stale. Dates, prices, screenshots, references to features that no longer exist. This affects whether people trust the page as much as whether Google does.
What not to do
Do not change the URL. If a refresh includes a new URL, you have thrown away everything the page had accumulated and started over — exactly what you were trying to avoid.
Do not update the date without updating the content. It is a transparent tactic and readers notice faster than search engines do.
Do not consolidate too eagerly. Merging two pages that rank for different things loses one of them. Merge when they compete for the same queries, not when they are merely on the same topic.
Measuring it
Track the specific queries the page ranked for, before and after, in a fixed window. Site-level traffic will not show you whether the refresh worked, because everything else moved too.