You can put a PXE Rep in a holding Queue, in which case all devices in its subnet will boot once to WinPE Managed. This is fine if you boot every device once and let them boot all the way to WinPE and send a miniscan. Once every device has PXE Booted once, then only new devices on the subnet will boot to the holding queue.
Or you can put a single device in the holding queue.
Try the single device way, it looks like it is closer to the feature set you want.
You can also do a VBoot, where you push a task to a live machine and instead of PXE booting, it copies the WinPE to the hard drive and boots off it that way.