Hey Jeff -
There isn't an API to do this - you'll want to our command-line tools (which are scriptable) isntead. tabcmd runschedule or tabcmd refreshextracts can both get you to where you want to go.
Thanks Russell. Where are the commands ? Are they in the server side ? Is there any way to refresh the data from client side just like I could do it in the web ?
tabcmd can be installed locally on the client, so yes - you can refresh an extract from the client.