Im my case the springs were cleaned up, new leaf installed, new clips and new bushings. According to the shop foreman, the arch of my springs looked ok. The free arch was about 5", measured from the center of the eyes to the top of the spring pack. During the disassembly and rebuilding, the individual leaves are inspected for cracks, corrosion, and defects.
If you need to have your springs re-arched, you might as well get new ones. There are very few shops that can do the heat treating required to restore springs to their original condition. Avoid any shops that re-arch the springs by bending them on a 'bulldozer'. Without the heat treatment, re-arching is only a temporary fix.