Mental game
How do I beat someone who beats me most of the time?
There are different ways you can approach this, First try to relax and just have fun dont think about winnning or losing; just think about playing good. I find it sometimes good to forget about the score and just hit the ball.
If you think about it too much your losing on the time to react to a ball, table tennis is a hit and react game not too much thinking should be involved.
Try new things, hit to the weakness of your opponent if he\she has one.
Key is have fun!