You can take the subway to get off at Central Station first and then go out of the station to the Exchange Plaza through the Exit A. At the Exchange Square, there are buses to go to the Repulse Bay, including Buses No.6, 6A, 6X and 260. The bus ticket costs around HK$7.9. As the bus driver doesn't give you change, you'd better prepare some small money before getting on the bus.