I think this would be a nice feature. Possibly it could run in the background so the fresh results are already prepared before the user switches to the Monte Carlo page?

And even if it’s not reasonable to automatically re-run the Monte Carlo when inputs change, display some sort of indicator (Red explanation point inside a triangle? Red back ground for the refresh button?) near the refresh button to remind the user that the current plot contents are out of date and need recalculation. It’s easy to accidentally assume the displayed results are current.

This is an interesting feature idea. Assuming it wouldn’t be a drag on performance, perhaps you could even re-run the monte carlo simulation in the background, and display the success/failure rate on the deterministic view, just above the plot.
Maybe this could be an advanced settings that’s off by default, and/or uses fewer cores when running in the background.

I don’t think it needs to re-run each time a change is made, but perhaps just an indicator to let the user know that they are viewing a stale result in the case where things have changed since last run. This includes a change in currency type (actual vs todays).