Master Metered/Separate Metered Multi-Family

[Brett Riemensnider]

Hey all. I am renewing a lease for one of my tenants and the new lease states he will start covering his own electric and gas. 
Unfortunately it looks like the electric is individually metered, but the gas is not. 

Now we have our new terms coming up and I do not know how to alter the lease. Is this something I am even allowed to do? As stated before, the lease lists gas and electric being paid by tenant. What are my options?