Is it possible to have shiny update a plot with additional data as a long running function progresses? E.g. if I am running a simulation, can new runs be added to the overall results incrementally and the plot updated?
You need to run your simulation as a different R process (i.e. not within Shiny). Then you can for example write the results periodically to a file, and use
reactiveFileReader to detect change and update your plot.