I have just joined and am looking for some advice about my cat. She is female, spayed, 9-10 years old and has always been an indoor cat. She mostly eats dry food, with wet food as a treat once or twice a week. I try to buy good quality food, aimed at indoor or senior cats. She's always been a bit of a puker, I think because she's indoors and she over-grooms. She had cystitis a couple of years ago which she got over easily after an injection at the vet and some medicine at home. We were alerted to that illness as she kept sitting in the litter tray for long periods of time, without actually doing anything.
My concern is that sometimes she will get in the litter tray, and then get out without doing anything. She's not lingering like she did when she was ill before. And she is still peeing and pooping, eating, drinking (although she never drinks as much as I think she should... she likes to lick water off her paws... cute, but not practical), playing, cuddling, purring... nothing else has changed. So I'm not particularly worried, but it just seems a bit odd.
Any advice on what to look out for, dietry change suggestions, or puke-preventing tactics would be appreciated

I do have another cat - a male, neutered, 11-12 years old. He's also a bit of a puker, but no other issues, other than slightly overweight. He will occasionally chase my girl, but they mostly ignore each other, maybe a bit of mutual grooming now and again.
Thank you!