Would navies modernize or replace old battleships?

Would navies modernize older battleships with radar, rockets, and new guns, or build replacements?

They would mostly replace World War I ships, then modernize the much newer battleships produced by continuous 1940s construction.

Most World War I-era battleships would leave service during the 1940s rather than receive endless modernization. A sustained British program could bring roughly four new ships into service in a productive year and replace the old battle line over about a decade. The ships receiving 1950s radar and guided-weapon refits would then be relatively young hulls built during the long rearmament. This differs from the historical postwar problem of modernizing survivors after construction had been interrupted and many capital ships destroyed.