Welcome to planDisney, Jackie,
Congratulations on renewing your Disneyland Resort Magic Key pass. You're in for another year of access to a "world of yesterday, tomorrow and fantasy!"
Yes, as long as the new Magic Key pass you wish to have as an upgraded pass is currently available for new purchase, you may visit one of the main entrance ticket booths to complete the upgrade. The new pass must also be of equal or greater value. When you upgrade, you will pay the difference between the full price of your current price at the time you originally purchased it (or in your case renewed it) and the current full price of the new pass. If you financed your current pass with interest-free monthly payments, that contract will not be changed. You would continue to make those same monthly payments for the remainder of the 12-month term. When you visit the ticket booths, the Cast Member there will verify the photo attached to your current pass matches you. But it's also a good idea to have a photo ID with you, just in case. The upgraded Magic Key pass will have the same expiration date as your current pass.
If you are a Magic Key holder within your renewal window, up to 30 days before your current pass expires, you have even greater flexibility. At that time, you may upgrade, or downgrade, to any available pass type, even if it is not available for new sales. If you are eligible for a monthly payment plan at that time, your payment plan would be reset to divide the price of the pass renewal into 12 equal payments.
Tony's Tip: It seems like every time we visit the Disneyland Resort, there's some new activity, special offer, or giveaway for Magic Key holders. I follow the official @DisneylandMagicKey accounts on social media platforms and monitor the Magic Key portal on the Disneyland mobile app to keep up with all the news and information.
Enjoy your year of magic at The Happiest Place on Earth, Jackie!
~Tony