Recrawling in nutch 2.x

[Ali rahmani]

Dear Guys,
we are working on search engine ,and we have to juest version 2.x(due to its 
ability to connect to HBASE). we tired tens of re-crawling scripts but non of 
them works. Is there any re-crawling scrips for nutch 2.x. 
We also added "db.fetch.interval.default" to "nutch-site.xml" file but dose not 
have any positive effects. 
Regards,