Think of Imawa no Kuni no Alice Retry as milking the success of it's predecessor in order to make a lackluster sequel that doesn't really add anything to the story.
Just like Imawa no Michi no Alice, the only reason you'd read Imawa no Kuni no Alice Retry is because of the success of the original series. Not to say that Imawa no Kuni no Alice Retry is actually bad, it's just that it pales in comparison to the original and doesn't add on to the main series. It's just... there. It's a short 13 chapter run which doesn't really do anything but add one last game to the series. Was the singular game good? Yeah, it wasn't that bad at all, but the series doesn't culminate to anything else. I don't know if it got axed or whatever, but the sequel just ends just as soon as it started.
Like I said earlier, the game of death that is shown in the manga isn't bad--it keeps up the spirit of the Alice in Borderland games that we're all familiar with, but if I'm being honest, the series kind of ran its course already. Perhaps if the sequel was long enough to be its own standalone, I'd get it, but that's not the case.