Tenants son will be 18 soon

My good tenant (5 years plus) has a son who will soon be 18.
The periodic tenancy signed in 2016 did not name him as he was underage.
Should I set up a new lease including him?

Check if your insurance or mortgage terms require all adults to be tenants. Otherwise I wouldnt bother. Its likely that he wouldnt pass referencing anyway. You should do a right to rent check when he turns 18 though.