Can a car dealership change your lease agreement?

It is hard to provide you with definite answer without reviewing your lease agreement (because it is possible that the lease agreement could leave the car dealership the right to fix mistakes in the lease).  That being said, if the lease agreement was signed, it was a valid contract and it should be enforced at .10 cents a mile.  Review the agreement, does it provide dealership right to revise/redo agreement?  If not, tell them that you have enforceable contract and do not agree to signing another one.  If they get aggressive with you, contact a local attorney to assist (and perhaps write simple letter to dealership).  One last thought, if you are getting pressure from sales person, you should call and send letter to dealership general manager.  State that you have valid contract and don't appreciate pressure from dealership.  State that you have had good relationship with dealership and would like to continue relationship for servicing of vehicle --but, if they continue trying to redo agreement, you will not only find another location to service car, but also you will post your displeasure on social media sites like Yelp and Google+.