or, just switch up to the latest release's repository, ... or is that unadvaised behaviour in ubuntu-land?  ... or mint-land[/edit]
i used to keep various ubuntu systems going continuously for years without need to reinstall this way. been a while, but iirc, /etc/apt/ is the dir where you can set repository sources and other things.
... yes there's the chance (at least from my past experience years back) that things can go a little bit janky, just a chance. but for changing one line in a config, rather than doing a complete system reinstall, it might be worth trying...?
though reinstalling to get everything fresh n clean, just as canonical want you to have it, that's an option too, sure.
if you dislike frequent (anual/bianual) reinstalling in this manner, and want to still stick to official paths, there are LTS releases too.
long term support. what's that then, 3 years? 5 years? (or at least there used to be, lol, i'm not checking my facts, just chirping some suggestions, some pointers, some possibilities).
welcome to linux questions!
what am i saying?! reinstalling is good fun and good practice!
you've got a backup
of all your important data, right
? no problem, go for it. should be straight forward enough and ferry you through the process. everything should "just work".