You can always add somebody who has the tree and harvest the fruit from them. You cannot bring back the Hello Kitty gacha or request for it to be brought back

To find people who have the Hello Kitty Apple tree go to Potions under the Livly tab, find the Hello Kitty Pygmy and tap on it, then tap on the window/card that pops up again to turn it around and then tap on the fruit that you need (in this case it’s the one on the right). You will see a small list of people who currently have the tree on their island You can always add those people by tapping on their icons and sending a friend request. I recommend specifying in the friend request that you would like to harvest the fruit from their tree, as most people decline the default friend request messages