Weather strip along bottom of window
Mine leaked as well, until I added some 'packing' to the space between the lower window strip along the bottom of the glass on the outside. There is a gap there, between the seal that touches the glass (acts like a wiper when the window goes down and back up), and the part that lies along the edge of the door skin. It's kind of covered with a 'flap' of rubber attached to the 'wiper' part. Fill that gap with a length of black nylon rope of about 1/8 inch diameter or so (may take a bit of diameter experimenting to cope with your particular seal / window situation) and it will now seal the rubber strip against the glass again, as when the car was new. You can also tell a difference with the window glass wiping action improved. This will reduce the water flow into the door, but depending on the condition of the plastic sheet liner, it may still leak some.