Unless you travel with it constantly, it really isn't that big of a deal to leave it plugged in. My laptop battery wasn't replaceable when it died two years after I bought it new. Been working without it for almost ten years.
Of course it sounds like you are running it for more demanding work requiring the latest, greatest cpu and gpu. Yeah, a new PC should help run AI much faster.
I should probably consider something similar considering my PC was originally optimized for win7, and it barely runs win10. Can't even run steam games and discord on it well. It gets work done on a web browser and basic documents and image file organization, which is most important for me. My phone almost does more; in some ways it does.
Really I want a Linux desktop pc, but I am afraid of the learning curve or running into scenarios where software simply won't run, or my laptop bak hard drives can't be read.