Why is my car leaking antifreeze?

Don't know "why" but you need to determine where it is coming from before you can fix it. If it is coming from the hose you replaced, make certain the hose is fully pushed on the block and the radiator fittings and re-tighten the clamps. Also check the coolant in the reservoir and add coolant up to the full line.

Go to a car wash and clean under the front of the car then fill it with a/f and look for where it is specifically leaking from. The water pump likes to leak when it begins to fail and is located inside the timing cover so it's leaking cannot be seen except for the position of the puddle underneath. If you have a leak from just behind the main belt pulley (harmonic balancer) the water pump is bad

How about the lower radiator hose, radiator, heater hoses etc?