Complex sentence: Unfortunately in that same year she had closed down the gallery due to poor health, and only returning to business again in 1988 as the "Della Butcher Gallery" in Cuppage Terrace.
Split into simpler sentences: Unfortunately in that same year she had closed down the gallery due to poor health. In 1988 she was back in business again, reopening her gallery as the "Della Butcher Gallery" in Cuppage Terrace.