why thye fuck would you keep adding coins to it if you dont know the password?
More likely you have obtained someone elses wallet.dat file that they have encrypted and they do not know you have a copy of this wallet.dat so they are still using it, and you do not know their key but would quite like to access their coins.
send any new coins to a new address, sure you may remember the password but hedge against that possibility with another wallet, please. for my sake, for my sanity, do it for me.
More likely you have obtained someone elses wallet.dat file that they have encrypted and they do not know you have a copy of this wallet.dat so they are still using it, and you do not know their key but would quite like to access their coins.