There are no miracle cures that can be sprayed on the fields to increase survival or yields. Make replant decisions carefully. The very thing that makes cotton so complicated to manage, being an indeterminate perennial, gives cotton an advantage over other crops when hit by hail. Cotton can recover much better from hail damage than soybeans, and especially corn. If there is a doubt, keep it.
Cotton can really come back.
When examining a hail-damaged field examine the plants to see what percent have a terminal, what percent do not have a terminal and what percent are cut off below the cotyledon node. Those cut off below the cotyledon node will probably not recover. Those that do not have a terminal will probably recover but produce a crazy plant with many branches. These plants can produce cotton but will mature very late and thus be subjected to the problems associated with late cotton, i.e. insects and weather. Examine the stems of those seedlings which may survive.