Hello Khelvan, and welcome to Seven Forums.
Unfortunately you will need to do a clean reinstall for each new build of Windows 7 released. Windows Updates will not update to the new build.
If you have signed up with
Microsoft Connect as a beta tester, then you will be able to download the official releases from there. Otherwise, you will have to take your chances with the torrents.
The beta versions of Windows 7 will stop working on August 1, 2009. After that date, there may be a new build (ex: Release Candidate) to use instead. Otherwise, we will need to purchase it when it released to retail.
Hope this helps,
Shawn