This extension is a node that directly expands the functionality of KSampler, rather than being in the form of a custom node. [w/Workflows created using this feature are not compatible with other users.]
https://github.com/licyk/ComfyUI-Restart-Sampler
git clone https://github.com/licyk/ComfyUI-Restart-Sampler
comfy node install comfyui-restart-sampler