Since you have a 2001, I think I know what you mean. Let me describe it, and if I have it right a replacement should not be too hard. My boat has a cabin door made of white Starboard™, with a half window. I would think yours does too. The door sits flush, so to do that it is in a "depression" in the cabin bulkhead. This leaves a space above the door that is also inset. So, a "dummy" piece of Starboard is placed here to make it flush with the door. Is this the piece you mean? Only thing that seems questionable is that my bimini attaches to awning rail that is on the cabin roof, and you mention attachment points. Anyway, if it is the piece I referred to above, then you should be able to use matching Starboard. There is white, and then I think the cream color is "Seafoam," but check for yourself (and see of course what color your door is).
Otherwise, if you mean the plastic "track" that the bimini "rope" slides into (if you have that style), then that is called awning rail, awning track, or Keder rail or track and you can get it at places like Sailrite.com. Note that on some of them the groove is "on top" and on some it faces the side (which would be aft). You'll likely want to match what you have.
Here is a photo that shows the first thing I thought of when reading your post, which is the above-door "filler piece" -- although it's not above the windows but only the door, so (?). I'm not at the boat right now to look at how it is attached, but my guess is that it would be fairly straightforward.
