Do I need to reinstall pearOS every time there's a new release?

No. pearOS NiceC0re is Arch-based and runs as a rolling release - there's no more base-hopping or reinstalling with every version like on the old Debian-based pearOS.

Just keep your system updated:

sudo pacman -Syu

You'll keep the pearOS branding, apps and theming through every update - no reinstall needed. New ISOs are mainly for fresh installs or for people who want a clean start.