If you feel the brakes don't have enough bite, look into alternative pads. Theyre most likely to make the biggest difference. Fluid only a few months old is highly unlikely to be your issues unless someone is not bleeding your brakes fully, or theres some other reason. You don't need to replace brake lines unless they are shot. You might replace any rubber brake line parts with say Goodridge hoses, but in your case its better to find out the reason for your issue rather than just throwing money at everything. Its a whle since you posted your story, so would you like to bring us up to date and tell us your findings?