Now that we are adding a request to have all portals removed from a client’s energy, will a single request be effective to have this done on all prior clients, and for the task to be implemented repeatedly if necessary, until all clients have been upgraded?

This is a fine idea and in general, the answer is “yes.” In the case of those who have done many, many sessions by now, like yourself, wording the request to have it repeated as needed until fully complete, will act as insurance, and this will indeed guarantee a complete removal for all prior clients takes place.