I tried to follow your suggestion by creating a journal named "save_monitors.jou" that plots and saves my monitors. This journal has the following structure (I am only showing here a snippet fore illustrative purposes):
plot/residuals yes yes yes yes yes yes yes

/display/save-picture "monitors/residuals.png"

/solve/report-plots/plot fan_inlet_totalp-rplot
/display/save-picture "monitors/fan_inlet_totalp-rplot.png"
In this journal the residuals and the report plot "fan_inlet_totalp-rplot" are saved in the folder "monitors". To make Fluent read the journal I used the console command file rj save_monitors.jou.
Thank you for your suggestion, Rob.