Why the same novel is reproduced repeated to films or video films

hmmm. i wouldn't think it that way.

for me, if it's a classic like romeo and juliet, i would think that it was meant as a play anyway. and it's a script that will never get bored and is ever green.

honestly, would you want to watch a film that starred actors and actresses that have been long gone (eg. Audrey Hepburn - she's an old classic actress but she didn't act in romeo juliet though ) or would you rather watch leonardo and claire danes?

in this money making world, anything that makes money is a GO. since classics are mostly widely loved and well-known, directors would of course go all ahead to film them.