ldap imported users synchro update

[adminexploit]

Hi,
I've about 1000 users imported from Active Directory ( too bad for my karma). I'm unable to authenticate on proxy server each time I change my password on AD. Today, I discovered a magic option to make a user sync from AD and I can connect to proxy server. Is there a way to make users sync from AD/LDAP service automatically ? I found a topic where people had same question a couple of years ago, but they didn't get answers.

thanks for your helps