Can I be charged full legal rent if I have a preferential rent rider signed with the original lease?

Can a landlord charge legal rent if I have a preferential rent rider signed with the original lease on Nov. 2003 that states: Instead of the legal regulated rent set forth above, owner agrees to charge and renter agrees to pay monthly preferential rent of $1210 and shall pay this same amount as security deposit. If renter chooses to renew the terms of this lease, this preferential rent amount, plus all other lawful increases, shall be used to calculate all applicable increases to establish the renewal rent. Thereafter, each successive renewal rent shall be calculated based upon increases to the most recently established renewal rent for as long as the renter remains in occupancy. I have remained in occupancy. The apartment has not reached the "deregulation rent" threshold of $2000. I have always been offered preferential rent with the legal rent quoted for a future vacancies. I have signed no other riders concerning this preferential rent. I feel the intent of the rider was for as long as I remained in the apartment. Can I be charged full legal rent on my upcoming 5th renewal after always paying preferential rent?