You should be able to keep your saves files by just installing 24 over 23 as they share the same file/folder structure. As long as you're not deleting the old app beforehand. You can usually find your saves under \Android\data\com.nowandthen.myapp\files\saves
If you've lost them, I have a file with saves from an older version you can try out here: https://mega.nz/file/uGpgDZTQ#c7dTq1fB_c5_oPHOpxIas1HJnVJhnirsxTtD2VqgWiY
You'll have to unzip the saves and move the files into your save folder after you install the newest version. After the game installs, there'll be a folder somewhere like \Android\data\com.nowandthen.myapp\files\saves . Place the saves there. When you load up, these should be under page 9 and 10 of saves so that they don't interfere or overwrite any saves you might have had.