there is answer in FAQ (.... faq.html#Q100)   but unfortunately i have such
problem: i have limited time to use the computer so i can not wait for mirror
to complete. so next time when i start - winhttrack trying to continue , but
it starts to update already downloaded files. and i will never reach the end.
what can i do? for example in wget program there is option -nc (no clobber) to
leave downloaded files intact and do download other files. or -N option for 
downloading only newer files.    is there such option in winhttrack? i did not
find it by my self. 
thanks 
best regards