Encrypt exisiting database in Android

I have an app already published in Play Store. Now, I want to encrypt the database of the app.

I know about SQLCipher for Android which can do this for me. But the problem is that my app is already used by a lot of users and they have lots of unencrypted data inside it.

Now, how can I use SQLCipher with an existing unencrypted database? So that all my previous data gets encrypted without any problem and new data gets going as it should.