I had a composite filling for my first molar a month ago, but i still have pain on biting, and i repeated my filling but i still have pain what i do?

Re-evaluate tooth: Let your dentist know that you are still having pain. Have him\her re-evaluate the filling to make sure the bite is not the problem, nothing is broken, there is no tooth fracture, and the pain is not coming from an adjacent tooth. As a last resort, the tooth needs to be evaluated to see if it requires root canal therapy.

See your dentist: See the dentist that did the filling. Sometimes it can be as easy as just adjusting the bite and the pain will go away. If the filling was deep, then the nerve could be involved and you would then need a root canal. The dentist that did the filling would be the best one to contact and evaluate.

Several things.: The symptom you describe can be one of several possibilities. If the surface of the tooth that the filling is bonded to was not adequately treated prior to placing the filling, you will be biting sensitive. If a part of the tooth is cracked you can have the same problem. Same for a filling that is too tall or an abcessed nerve. If your dentist can't diagnose the problem, see another one.

Check bite: The filling could be high so have dentist adjust the bite or the cavity could be deep causing nerve sensitivity which could to a root canal.

Wait.: The tooth has been drilled on twice in the last few weeks. It might be sore just because of all the dental work on it. However, if the filling was deep and close to the nerve , it might have caused some irreversible damage to the nerve and it may need a root canal. If you can wait it out give it more time for the sensitivity to go away. While waiting try to favor that tooth as much as possible.