I offered a lower rate to a client for drop ins, does he need to make a new request or can I send him a request?

I just met with a client who has 4 dogs. He requested drop ins 3x a day for 3 days. The total price is pretty high; after talking for awhile I offered to drop my rate because his dogs are all very very low energy and relaxed. Since I am changing my rate to change the total, Do I need to ask him to make a new booking request that will reflect the lower rate? Or can I send him a new request? He is a new client that I have not worked with before.