Update android game with new levels without replacing database

So I've published a game for android users containing 400 levels and 2k users have completed or are playing it since. Now I'm going to update the game with 600 levels, but I don't want current users to lose their info in database. I just want to add more levels to the database if it exists in their phone.

I'm using this code not to let database get replaced if it exists.

     public DataService()
     {
 
         const string databaseName = Constants.DbName;
 
 #if UNITY_EDITOR
         var dbPath = string.Format(@"Assets/StreamingAssets/{0}", databaseName);
 #else
         // check if file exists in Application.persistentDataPath
         var filepath = string.Format("{0}/{1}", Application.persistentDataPath, databaseName);
 
         if (!File.Exists(filepath))
         {
             Debug.Log("Database not in Persistent path");
             // if it doesn't ->
             // open StreamingAssets directory and load the db ->
 
 #if UNITY_ANDROID 
             var loadDb = new WWW("jar:file://" + Application.dataPath + "!/assets/" + databaseName);  // this is the path to your StreamingAssets in android
             while (!loadDb.isDone) { }  // CAREFUL here, for safety reasons you shouldn't let this while loop unattended, place a timer and error check
             // then save to Application.persistentDataPath
             File.WriteAllBytes(filepath, loadDb.bytes);
 #elif UNITY_IOS
                  var loadDb = Application.dataPath + "/Raw/" + databaseName;  // this is the path to your StreamingAssets in iOS
                 // then save to Application.persistentDataPath
                 File.Copy(loadDb, filepath);
 #elif UNITY_WP8
                 var loadDb = Application.dataPath + "/StreamingAssets/" + databaseName;  // this is the path to your StreamingAssets in iOS
                 // then save to Application.persistentDataPath
                 File.Copy(loadDb, filepath);
 
 #elif UNITY_WINRT
         var loadDb = Application.dataPath + "/StreamingAssets/" + databaseName;  // this is the path to your StreamingAssets in iOS
         // then save to Application.persistentDataPath
         File.Copy(loadDb, filepath);
 #else
     var loadDb = Application.dataPath + "/StreamingAssets/" + databaseName;  // this is the path to your StreamingAssets in iOS
     // then save to Application.persistentDataPath
     File.Copy(loadDb, filepath);
 
 #endif
 
             Debug.Log("Database written");
         }
 
         var dbPath = filepath;
 #endif
         _connection = new SQLiteConnection(dbPath, SQLiteOpenFlags.ReadWrite | SQLiteOpenFlags.Create);
        // Debug.Log("Final PATH: " + dbPath);     
 
     }

Also I've created a filed in database keeping database version to check what version the user has (like the version with 400 levels, the one with 600 levels or maybe more).

What I don't know is what is the best solution to add more records to an existing database. Has anyone got a solution?