Nothing special to do ..... just let the machine do the work and if you don't want to wait just use 'apug' or 'api gnome-icon-theme-cybertechno' if you haven't got them already.
The 'cybertechno-icons' aren't specific for any release and can be used on any Elive version ..... I just repaired and added some to be usable for a next (3.8.34) release.
It's only about what is installed and run by default .... you're always free to customize in any way you want.
but talking about next beta's, you don't really need to reinstall, so elive automatically upgrades itself in the best / smart way
if there's new software or packages included, then you need to install them yourself or reinstall the OS, but that's not very common
on the other hand it is actually suggested a reinstall but not in every relase, let's say every 10 releases, the system is more clean and there's a few things that could be included only when reinstall (there's a specific thread talking about that)
if you ask about bookworm especifically, you must simply watch the elive news to knew -when- it will be added (then yes, you need a reinstall, or at least is the suggested way for this upgrade)