You would need to ID the trouble first. Post pix in the Garden Clinic Forum.

tj

Heuchera rust is very common. And it's pretty darn easy to ID - the rusty orange-yellow pustules are very obvious, especially on the back of the leaves. The disease is favored by lack of air circulation and high humidity. I might remove any mulch and surface soil in the area as it could contain spores. Otherwise make sure the plants are well spaced and be careful with your watering practices, avoiding the foliage as much as possible. Any fungicide registered for rust on roses can be helpful on heuchs as well as long as you spray before any signs of the disease are obvious.

Here is a picture of it. This was taken a few weeks ago. The plant is doing worse since then.

That doesn't look much like rust. Can you post a photo of the underside of the spotted leaves?