I don't think I could survive very long without a pet. I'm guessing you've only had one pet; Crookshanks. Once you adopt a second pet, before or after the first one passes, you realize it isn't like replacing AT ALL. No cat is ever going to replace the place you have in your heart for Crookshanks. You will however, form a new place in your heart for your new pet. It's like friends. If you had one wonderful friend that you loved so much, but they passed, you would turn to your other friends for comfort, but they would never ever even kind of replace your friend that passed.
We got Milly when I was 10. I loved her so much. When I became a rebellious teen, I didn't always appreciate her as much as I should have, but I was living at home when I was 21-23, and by that time we were incredibly close again. My girl would even bark and get my parents up, and make them call me home if it got late and I wasn't there to snuggle. She was my first pet, and I grew up with her, and she was one of the loves of my life.
The day she passed, I absolutely could not deal, and I couldn't stay in my house without her there, so I asked my boyfriend to come pick me up and take me to his and his families house, where he lived. They allowed me to use his bedroom to cry and nap throughout the day, and their dog, Jaxy, seemed to know what had happened. I always say it's like my Milly came to him and asked him to take care of me or something. I had always known him and loved him, but things changed that day. He would pop his head in every couple hours, and come nuzzle me, and wag and snuggle me, like all of a sudden I was his person too. He was certainly not Milly, and wasn't trying to be, and didn't replace her at all, but he was there to get me through it, and he quickly formed a new special place in my heart, and he became my Jaxy. After that day, we had a special bond, and he treated me as his forever after that, even though he just wouldn't totally let me in before that. For the next 4 years or so, we had an incredibly bond, and he came over to my house whenever bf's family would allow, so several times a week when bf came too, and I would beg to have him steal Jaxy, and Jaxy was always so thrilled to come. Even though I didn't own him like the family, he was my boyfriend's boy, and my boy for sure too at heart I feel sure. He didn't replace Milly in any way, but he got me through it, and I loved him as I loved her, like he was my own, just in a different way. I delighted in doing fun training sessions, cuddling, bringing foster doggy pals from work for him to play with, I just loved doing anything with him. Even when BF was away on vaca for a few days or a week, bf's fam would let me come over and spend time with Jaxy. They would sometimes pretend it was because he needed a bath and wondered if I'd want to or something, but it was them being kind bc they knew how attached I was. When Jaxy got fleas, I was more than pleased to spend several days disinfecting Jaxy and their house, even though they would have otherwise. I loved that boy so much.
He passed at about 10 years old, and it broke our hearts. I'm still so grateful to him, my baby boy, and his family, for allowing me to love him and be such a part of his life. There were 4 kids, so the parents and kids were always arguing over who could spend time with Jaxy that day, and take them around with them.
I got a little caught up reminiscing, but my point it, if you loved your pet, and miss the companionship of your beloved animal, another pal isn't replacing them at all. Jaxy helped me through my loss, but it was completely separate from the love I felt for my Milly. I never even felt guilty or anything, because it was a completely different relationship because he was a completely different dog. My Milly would have been so pleased that I had a doggy friend to help me through, and never would she have felt replaced. Jaxy made me think of her even more, because of their similarities and differences, but it was just totally different.
Don't be afraid of replacing your pet. Wanting someone to love is natural, and your cat would feel honored that you found such love in him that you would like to offer a home to another cat, and it help remind you of him and all the similarities and differences, and treasure his memory. It might feel like you'd replacing before you adopt, but after it just doesn't. It feels like your pet is smiling down on you happy there is someone to take care of you, and happy that it's making you think of all the good memories with them. And they are going to be so different, it's not going to be a replacement. But you will love them in a totally new way.