HTC released the RUU file for Sprint’s One M7 manual Lollipop update
You will have to download the 1.5 GB file to your PC and be sure the device is detected when you plug it in. Then you will have to install HTC Sync Manager where you will find the necessary drivers. Then you just launch the file and it will show an installation wizard. This action is completely re-flashing your phone, which means it is likely that everything will be deleted. Be sure to back up your files before manually updating.