You may convert your .apk file to a .zip file but when you do, you will see that all of your lua files will already be compiled so there is no way to access your lua files through an apk. I ran into a similar problem once and discovered I couldn't recover my lua files.
You can then try to decompile the lua files using luadec
. If you're on 5.1 then this works: https://github.com/sztupy/luadec51/wiki Note that depending on you've scripted it not all lua files will compile to the right text, and definitely not all lua files will decompile correctly. You will have to go through each lua files and check for decompilation errors (they are commented when decompiled)
In the future, consider saving all your project files in a Dropbox directory AND use version control. If you use hosted version control (Assembla, GitHub, Bitbucket), then that is better too. This means you get local copies, multiple copies of copies in Dropbox and hosted copies at your service.
Good luck!