How many times do you get to save vs. an illusion?

[Particle_Man]

If you interact with it once and fail your save, do you get to save against the illusion every time you interact with it again, or are you stuck believing the illusion unless you get incontrovertible proof or are told by someone else that it is an illusion?

What counts as an interaction? Every action a person can take against an illusion in a round? Every attack (so a full round action that is 2 attacks would merit two saving throws?) Do attacks on the illusion that miss count as interactions? Do "attacks" by a figment that "miss" count as interactions?

 

[Ashtagon]

My personal take on it is that you get a save:

* The first time you interact with the illusion.
* Each time a new person tells you it is an illusion.

Incontrovertible proof lets you immediately see through the illusion.