Yesterday, Microsoft released the Windows 10 Insiders Preview Build 20201 to the Dev Channel which contains no new features, but a list of bug fixes and improvements. Along with this, the company also released a new ISO/DVD image for the same preview build so that the insiders can perform a clean installation on their PC.
If you are using an older build, either you can upgrade to the latest Dev build 20170 via Windows Update or perform a clean installation using the latest ISO. Here's how you can download the ISO image of the latest Windows 10 test build.