What you are describing sounds like your fuchsias have rust. First off if you still have any healthy plants move them away from the ones that do, a place that has good air circulation and spray them with a fungicide. I can only repeat what you have already done, if you want to try and save the ones that have rust, strip all the leaves off and despose in the garbage, do not compost the leaves. I would also cut these plants back and if not already done spray both the plants and soil with a systemic fungicide.

Rust could have come on one of the new plants you bought or could have come from something else, it's a good idea to inspect your plants on a regular basis and treat at the first sign. It might not be worth all the trouble but if you have hard to find varieties it worth a try.

The plants you think have died, if the had a decent root system all might not be lost, new growth could spring from the roots. I've had to deal with this a couple of times myself, keep the area clean around your fuchsias, give them good air circulation, when the new growth starts give them a weak feed of 20-20-20.

If fuchsias were more readily available my advice would be to scrap the lot and start with new stock in a clean and airy environment, but they are getting harder and harder to find so good luck with whatever you decide.

Annette

Here is a link that might be useful: Fuchsia Rust