Can I add polymeric jointing sand on top of the joint sand already in place?
For the polymeric sand to adequately firm up in the seams between brick pavers or stone, the full depth of the joint needs to be filled with polymeric sand. Adding a bit of poly sand on top of an existing joint sand already in place will only provide a shallow depth of sand with an activated polymer, making it unable to resist ants, weeds or washout/erosion. If you are retrofitting a patio with poly jointing sand, you should first clean out all existing sand from between the pavers (use a hose or pressure washer), allow it to dry, then apply the poly sand.
