[CharlesStevenson]

I guess it rather depends upon what you mean by 'died'.

It might be that topping it up & using it has shown up a leak & the fluid's gone.

Or perhaps as has been said, getting back to using it has caused the pump or another component to die out.

If you check on google / you tube you'll find some videos that show you how to check whether the air con's clutch is engaging (IIRC this can wear and therefore it doesn't engage correctly any longer)

You'll need someone to switch on & off the aircon whilst you look under the bonnet, the videos will show you what to look for.

As has been mentioned, the wear can be adjusted for by shimming, but that might not be the problem?