My castor oil plant was doing very well, but now seems to have become unhappy. It has black specks on the leaves and some of the leaves look at least partially 'crisp'. These aren't black spots on the leaf itself, they are actual specks of something. They don't appear to be bug/mites, unless they are so small that I can't make them out by eye.

I also had some new leaf growth, but much of that seems to have stopped or the leaves have fallen off.

I feel like I'm caring for it in the same way as before, when it was doing well, so I'm a bit puzzled about what's going on. The only change has been that I repotted it (the previous pot was very small), which I thought was the right thing to do.

Does anyone have any suggestions for what the specks on the leaves might be caused by? Or any of the ailments really. I'd love to get my plant back looking healthy.

Ricinus communis - commonly: castor bean.
The black specks look like sooty mold ..... which might be growing on honeydew (insect excreta). Have you inspected for insects? Look especially closely for scale and/or mites. Your plant really doesn't like being indoors, and it appears it's suffering from too much water in the grow medium. Have you been misting the plant? If so, the practice is more likely to create a problem than to fix or stave one off.

* How do you tell when it's time to water?
* Have you been fertilizing? If yes, with what (include NPK %s please).
* Does your home make use of an ionic exchange water softener (uses salt as the exchange medium)?
* What did you use as a planting medium/soil?

Al