Thank you for the compliment - glad to hear you like the application.
RMTV stores downloaded data in a database, to reduce the load on TheTVDB servers.
Obviously data can get "old", as you have noticed, so for that reason in settings you can set how "old" data is allowed to get (eg. "expires").
Look in "Settings" under 'Finding TV Shows". There is an option "Cached Episodes will expire in X days".
By default this is set to 7 days and after those 7 days RMTV will reload data from TheTVDB when you're accessing that particular TV Show.
You can set it to "always" expire by entering the value "0".
However, most TV shows are weekly, and setting it to 0 will generated an undesired traffic load for TheTVDB.
Instead of changing this value, you can click on "Force refresh" under "Episodes" list (next to the "Settings" button).
I just tried it just to make sure (had to switch to German because the show data in English is super limited it seems) and I can see the entire Season 14 (20 episodes).
Hope this helps