Yes, all Flowcodes are dynamic (with exception to Wifi Flowcodes) which means you can change the destination/landing page at any point in time. You can do this on the My Flowcodes dashboard (you must be logged in). Select the code you would like to edit, scroll down to input a new destination, and press save.
Enter your new destination.
The code itself will not be changed, but the destination will. This means you don't have to worry about re-printing or re-downloading your code. It will happen immediately, with no lag.