I recently renewed my lease for an additional year, just by signing a single paragraph stating the new lease end date and that all provisions of the previous contract remained in place.

After just a month into the new lease term, I needed to move out and informed my landlord that I would be ending the contract early. The place was re-rented with new tenants in, in less than 10 days from when I left.

The original lease had an addendum stating that a fee of 2 month's rent would be required for early termination of the lease. The landlord said this provision was still applicable, and I owe two month's rent.

Is the landlord correct, or would they have needed to have me sign a new addendum at the time of lease extension?

If the original contract stated that you owed 2 months for early termination. Then you owe for 2 months rent.

all provisions of the previous contract remained in place.

That answers your question.

On the other hand, the landlord is not allowed to double dip. So you need to find out when the new tenant's first rental period started. You would be required to pay pro rated rent from when you moved out to when they moved in. If the landlord refuses to pro rate, then tell them to take you to court.

But you should count yourself lucky. Most leases do not have early termination clauses.

... On the other hand, the landlord is not allowed to double dip. ...

So it has been said. But the enforceability of the early termination clause might depend on whether the landlord incurred extra expenses (such as advertising, etc.) because of the early termination.


... If the landlord refuses to pro rate, then tell them to take you to court. ...

OP didn't say, but the LL may be holding a deposit.