My landlord wants additional money to renew my lease. Is this legal?

If your written lease is expiring, then each party is free to renew at new terms. This means your landlord can ask for more money, and you can choose to find another property. This is what is known as a free market exchange where neither party is compelled to purchase or sell a product at terms they do not like. The fact that your landlord has asked for more money does not mean you cannot try and negotiate a lower rent amount. Ultimately, you might come to an agreement that is mutually acceptable. This is why a free market works so well and no one is forced to buy or sell. Best of luck.

Yes. You are essentially left to negotiate a new lease when the old lease expires.

The landlord can ask for more money but you do not have to agree. You can choose not to renew and move out. You cannot insist that he renew the same lease as before. You are free to offer that solution in addition to simply converting into a month-to-month term.