Nope, you have to re-download it. Also, if you're refering to the latest version (0.5), it's not available for Android yet
I think your saves might appear in your list, but loading an old save isn't recommended, since I haven't implemented save compatibility yet. I am planning on looking into it starting right now for upcoming updates. The Android version should be released at the same time as the public version, around the 26th of July.