If it's basically empty, I'd go ahead and open the fuck up. 10 years is about all you can get out of one +/- 5 years on average before it requires major service.
Flush it out the old oil, go with Nylog o-rings, replace the dryer, replace expansion device (orifice tube on GM I recall), fill with oil, seal it up, vac down, then charge. etc
The gay R4 compressor likes to leak from the front seal, GM redesigned this (and the compressor to the stepped port design) so it is far less leak prone... but then you'll have to purchase a new compressor to counter this. You can yank the clutch and replace the o-ring, I would if your compressor is good and on a tight budget.
Remember to run the A/C at least once a week during the winter for a good while, not just five minutes. This keeps the oil circulating and the o-rings lubed.