I would like to filter out just a new cards (without reprints) and vice versa in the specific set/deck. It would be very useful option for newbies in MTG like me.

I found just one option how to do it, so far, and it's not so straightforward:
1. choose specific card set in gatherer.wizards.com search database (e.g.: Born of the Gods); 2. click on name of the first card; 3. than click on expansion set name (Born of the Gods again). Finally you can see expansion symbols in the column on the right. (I don't know why it doesn't work in the first step already.)
(First reprint in Born of the Gods is Divination (Sorcery) first time used in 2010 Core set.)