I dont think you can re-do those, maybe you can but I'd not think its worth it.
Look thru the "audio" section here on the forum, there are threads about speakers (tho most are about the ever-failing rear speakers). The rears are HARD to find dual-voice-coil units, but l don't think the door speakers are all that special.

Be cautioned it can be the head or amp, but most of the time, it's just an ageing speaker.