There is no way you can do that, RAPT includes only compiled files in the resulting apk. Thus, you cannot change the file that doesn't exist.
Nevertheless, you can build an apk by yourself, it took about 2 hours for me. Install JDK 8 (not 10, it uses a lot of memory). Get to renpy.org and get the application and RAPT. When you install Ren'Py, specify a folder for your projects and than unpack the game into that folder. After that, it's not that hard to get it ready. Read the following after you set up Ren'Py and RAPT, but before you try to build an apk.
First tip: you'll have to unpack the game's images from an archive with rpa extract and, to make the apk smaller, delete the archive.
Second tip: add some memory in gradle settings before building the project. The file is <RAPT root>\project\gradle.properties. The line is "org.gradle.jvmargs=-Xms2048m -Xmx24576m", I'm sure I've set too much, but I've tried several times before the first success and did not delete the images archive.
If your build fails, before changing memory settings and trying again, you need to stop gradle daemon, the command is gradlew.bat --stop from <RAPT root>\project.