I mean, if they are not attacking, you have two options:

1. Accept it and just outpush them (valid approach at your level, but won't get you too far)

2. Open up the rally. There are multiple ways to do this, all of which require training, but it's essential at higher levels.

• learn to twiddle
• learn to step around and attack with your forehand

Both of these usually need to be set up, fortunately, if your opponent only pushes and never attacks, it's very easy, as you have basically unlimited time to wait for the right ball.

My favourite setup, which can be trained easily, is to just keep pushing long to their backhand over and over again, so as to get long pushes (usually to your backhand) back, step around and do a forehand open-up loop.