+1 Which parts are wearing out? You can easily replace the chain and cassette (although you probably won't find an LX level 7-speed cassette..)

If the stuff is really getting shot I'd look for nice used or possibly NOS replacements on ebay. Still cheaper than buying a whole new group. Plus the group you have is really solid, I see no reason to replace the stuff that works.

Also keep in mind that most of the parts in a modern group will not be compatible with your frame and wheels. Disc brakes, 10 speed cassette, etc.