clear cache and then reindex cache

Is there any way to clear the site cache completely and then automatically rebuild it ?

Some of the cache is automatically rebuilt when MODX refreshes it. The caches for each individual Resource can be primed by visiting each page on the site (wget might work here) or using a script like the following...

https://gist.github.com/opengeek/ec3f885cefe17e470aa1

However, this can take significant time depending on how efficient your site is.

That's what the RefreshCache Extra does, though it's slow and the display is kind of funky in some browsers. Even when the display is corrupted, it still works, though.

http://modx.com/extras/package/refreshcache

thank you gents, just what I needed.