You don't need to make Google update it. Google will find the links when they crawl the sites where they exist. If you're asking how do you make new links show up in the output from the LINK: operator or in the WMT Links to Your Site page, you can't. Google typically only shows a sample of the inbound links in the output of BOTH of those. They don't want you to know 1) which links they know about and 2) which links they actually count.