fix or replace 5th generation iPad

Like sberman stated, this is a subjective question. But on the surface…considering how old your iPad is and its usefulness waning as it will likely start experiencing lack of app support due to it’s inability to get iPadOS 17 it would e a good idea to upgrade to a newer one. Only you know what you can afford though so do what is in your budget and go from there.

Your question is like asking whether you should repair your existing car or purchase a different one. The answer is subjective. And, of course, you should only do what you can afford.

The 5th generation iPad was released by Apple seven years ago. It is currently classified as a vintage product.

Obtaining service for your Apple product after an expired warranty - Apple Support

It cannot accept iPadOS 17 or later.