Hi Bob
I haven't seen the new brochure yet but it should be out by the end of the month, so that will answer your question about 2013 dates and itineraries. Dates should appear online at the same time or slightly sooner.
Holidays are usually discontinued because they aren't popular enough so I imagine there was more interest in the rainy season. This wouldn't surprise me as Costa Rica is particularly lush and beautiful at that time of year.
Kind regards,
Olly, your editor