how to upgrade SQLite database in android project?

i have a database in my project and now i changed my database as new content , but database has not changed, Please help me to solve this problem

i just replace database file in assets folder my source code :

public class MovieDB extends SQLiteOpenHelper {
    String DB_PATH = null;
    public static String DB_NAME = "db_movie";
    private SQLiteDatabase myDataBase;
    private final Context myContext;

    /**
     * Constructor Takes and keeps a reference of the passed context in order to
     * access to the application assets and resources.
     * 
     * @param context
     */
    public MovieDB(Context context) {

        super(context, DB_NAME, null, 3);
        this.myContext = context;
        DB_PATH = "/data/data/" + context.getPackageName() + "/" + "databases/";
    }

    public void createDataBase() throws IOException {

        boolean dbExist = checkDataBase();

        if (dbExist) {
            // do nothing - database already exist

        } else {

            // By calling this method and empty database will be created into
            // the default system path
            // of your application so we are gonna be able to overwrite that
            // database with our database.
            this.getReadableDatabase();

            try {

                copyDataBase();

            } catch (IOException e) {

                throw new Error("Error copying database");

            }
        }

    }

    private boolean checkDataBase() {

        SQLiteDatabase checkDB = null;

        try {
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null,
                    SQLiteDatabase.OPEN_READONLY);

        } catch (SQLiteException e) {

            // database does\'t exist yet.

        }

        if (checkDB != null) {

            checkDB.close();

        }

        return checkDB != null ? true : false;
    }

    /**
     * Copies your database from your local assets-folder to the just created
     * empty database in the system folder, from where it can be accessed and
     * handled. This is done by transfering bytestream.
     * */
    private void copyDataBase() throws IOException {

        // Open your local db as the input stream
        InputStream myInput = myContext.getAssets().open(DB_NAME);

        // Path to the just created empty db
        String outFileName = DB_PATH + DB_NAME;

        // Open the empty db as the output stream
        OutputStream myOutput = new FileOutputStream(outFileName);

        // transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }

        // Close the streams
        myOutput.flush();
        myOutput.close();
        myInput.close();

    }

    public void openDataBase() throws SQLException {

        // Open the database
        String myPath = DB_PATH + DB_NAME;
        // SQLiteDatabase.NO_LOCALIZED_COLLATORS
        myDataBase = SQLiteDatabase.openDatabase(myPath, null,
                SQLiteDatabase.OPEN_READONLY
                        | SQLiteDatabase.NO_LOCALIZED_COLLATORS
                        | SQLiteDatabase.CREATE_IF_NECESSARY);

    }

    @Override
    public synchronized void close() {

        if (myDataBase != null)
            myDataBase.close();

        super.close();

    }

    // return cursor
    public Cursor query(String table, String[] columns, String selection,
            String[] selectionArgs, String groupBy, String having,
            String orderBy) {
        return myDataBase.query("pwp_singers", null, null, null, null, null,
                null);

    }

    @Override
    public void onCreate(SQLiteDatabase arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
        // TODO Auto-generated method stub

    }

}