I trust you have not been performing this procedure yourself???!! See an orthopedist and he will diagnose it and teach you how to minimize it....it may be an infection if it is recurring, or you have some other knee issue going on.
Have u tried applying heat onto your knee, this will not get rid of the fluid but may ease any pain, i think if you go to the doctors they can give u a basic medication to held the fluid to go hope your ok.
Do you wear a support band when you are running?