You could probably get some kind of lube down in there, but the cable is like $55 delivered. Not that it's hard at all to remove/replace, but why take it out, lube, put it back in, and hope that it works instead of just replacing it once?
Lube might get you another year or so out of it, but your original cable lasted you, what, 16 years? Replace it and never worry about it again is what I say.