Fix decay when the page still has real demand and a path back that a refresh can restore, and let it retire or consolidate when the demand is gone, the page is obsolete, or the effort exceeds the return. The decision is not “refresh everything that slips” or “let it all go.” It turns on a single condition: does meaningful search demand and a realistic route to recovery still exist for this page, or not?
A page is worth fixing when the topic still has genuine search volume, the page has earned authority you would lose by abandoning it, and the cause of the decline is something a refresh addresses, stale facts, a thinner angle than newer competitors, or drift from the current intent. In those cases the page has somewhere to climb back to, and updating it is usually cheaper and faster than building fresh authority elsewhere. The presence of demand plus a fixable cause is the signal to invest.
A page is a candidate for retirement or consolidation when the demand itself has dried up, the topic is genuinely obsolete, or the gap between the page and the current SERP leaders is so wide that closing it would cost more than the recovered traffic could ever return. When several thin pages cover the same fading topic, folding their value into one stronger page and redirecting the rest often beats refreshing each in place. Retiring is not failure here, it is reallocating effort to where return still exists.
Run the test page by page. Confirm the demand still exists, name the specific cause of the decline, and estimate the effort honestly against the traffic at stake. If demand and a path back both survive, schedule the refresh. If demand is gone or the cost dwarfs the return, retire the page or consolidate it into a stronger one and redirect, then put that saved effort where a page can actually climb.