3 room apartment SWAP to minimum 1 room apartment

My roommate is moving out and I would like a smaller place for myself. My current apartment is located in Charlottenburg at Richard Wagnar Platz, U bahn. 3 room and for 1200€rent, 3600€ deposit. Ich suche eine Wohnung in Berlin, zentral gelegen, aber ich kann auch anpassen. A plus would be a balcony or on the highest floor. I