If you have Windows 10 Technical Preview and didn't specifically set it to the "fast ring" -- symbolizing your desire to live on the bleeding edge of new releases -- the latest build of Windows 10 should install over the top of the old build as soon as you fire up the machine. If you left it on overnight, build 9879 (identified by a watermark in the lower-right corner of the desktop) should be ready for you this morning.
This "new" build 9879 should differentiate itself from the "old" build 9879 by being more stable. I see no difference at all in any features. The hidden tricks and fixes I discussed two weeks ago still apply. I can even reconfirm the sticking Caps Lock/Num Lock problem.
There was one patch applied to the old 9879, KB 3019269, which according to a tweet from Gabe Aul only fix a 0xAB blue screen for some build 9879 users. Aul had tweeted earlier that Microsoft would "make a couple of additional fixes" to build 9879, but it isn't clear if any of those fixes made it into the new version.
If you would like to perform a clean install of the consumer (not Enterprise) version of 9879, Microsoft has provided downloadable ISOs for English (United States and United Kingdom), Chinese (Simplified), and Portuguese (Brazil). The product key -- which you will need for an ISO install -- is NKJFK-GPHP7-G8C3J-P6JXR-HQRJR.
Note that the Windows 10 Insider Hub says, "We have also released a hotfix package to Windows Update to address a few issues seen in this build." Be sure to check Windows Update as soon as you have the ISO installed.
If you haven't yet taken the Windows Insider survey, hop over to the Insider Hub and click on the link.