Viewmodel does not change Livedata after first time

Question

I fetch data from Google Books API using Architecture components. This is simple app for search book's authors. The problem is, that when I create ViewModel at first, it observes data , but when I change query to search another book's author, it does not show anything. I tried to clear ViewModel before fetch another data, it works as I wanted, but I think there must be better way for this and if there isn't let me know :)

Here is ViewModel code :

class BookViewModel extends ViewModel {
private static BookRepository repository;
BookViewModel(String q) {
    repository = new BookRepository(q);
}



LiveData<String> getInfo(){
    return repository.getInfo();
}

LiveData<String> getTitle(){
    return repository.getTitle();
}

}

And here is the function that I call in Activity to fetch data:

   public void searchBooks(View view) {
    // Get the search string from the input field.
    final String queryString = mBookInput.getText().toString();

        if (queryString.length() != 0) {
            getViewModelStore().clear();
            BookViewModelFactory = new BookViewModelFactory(queryString);
            BookViewModel viewModel;


            viewModel=
               new ViewModelProvider(this,factory).get(BookViewModel.class);

            viewModel.getInfo().observe(this, new Observer<String>() {
                @Override
                public void onChanged(String s) {
                    mAuthorText.setText(s);
                }
            });

            viewModel.getTitle().observe(this, new Observer<String>() {
                @Override
                public void onChanged(String s) {
                    mTitleText.setText(s);
                }
            });


            mAuthorText.setText("");
            mTitleText.setText(R.string.loading);
        } else {
            mAuthorText.setText("");
            mTitleText.setText(R.string.no_search_term);
        }
    }else {
        mAuthorText.setText("");
        mTitleText.setText(R.string.no_network);
    }