Mary, I wouldn't just plunge the new plant in where the old plant died without maybe removing some of the soil and replacing it with new. Whatever killed the other plant might still be 'lurking'.
That's the beauty, but also a hazard of using Earth Boxes - they protect from a lot of stuff, but if you do introduce a pathogen inadvertently you need to make sure to get rid of it before re-planting or it's going to haunt you for a long time.
