How to tackle aging in a Buffy potential reworked sequel

I know its a long shot they even rework this, but if the reason for dropping the reboot was the focus on the new cast, why not going full returning cast members?

My main concern on the “vampires don’t age”, how would they explain returning Spike, Angel…

Maybe they could refocus it the other way around. What if they didn’t know it at the time but the slayer carried like an anti-vampire std that is innocuous to humans but would make vampires or other creatures age? In the few seasons that the series lasted it wouldn’t have been noticeable but it could explain them returning much older. I’d much rather see the old cast regroup with new plot lines, than see some new slayers.