If you're okay with using mods, QoL: Unknown allows for mid-layer saves that retain the world generation, traps, traders, etc... (https://itch.io/post/15369846)
Otherwise, vanilla has the `saveandquit` command which saves, but restarts the current layer from the start and regenerates the world on load. It also has the `continue` button when you reach the end of a layer, as well.