Upload & Sell: Off
... there is a box at the bottom of the LR Print module where you can add 'Brightness' and/or Contrast but you end up doing it blindly but I think something around 30-50 would be right.
Quick question for you on the settings, I see the sliders you speak of on the Print tab of LR5, but I'm not printing to a local printer, I'm sending the images to a print service. Is there a way to do this for the file export option? Or is this something I can request of the print service?
You are far better calibrating the monitor, adjusting the exposure or brightness after editing really isn't sustainable - at some point you will end up blowing highlights, for example. But...
You can 'print' to a jpeg file from the Print Module. It is under Print Job > Print to: > JPEG File. All the settings from the Print Module will be used in converting the image into a jpeg. It is really there so that you can add borders, inner strokes, cut marks, watermarks, and use the up-sizing and output sharpening prior to outsourcing the print, but it will retain the output brightenning and contrast settings too.
But all of that you will be doing blind,and it is far better to to see what you are doing.