Well, some aponegeton and Nymphaea bulbs will resprout when detached from the plant. Some you can detach the plant properly (when it has enough root) and just let them sit in the bottom of the tank. Do not replant until you see new plant growth. Doesn't have to be a lot of growth either. Just a little teeny weeny stub. That lets you know it's time to plant me.
Some Nymphaeas need to be place in a bucket full of moist sand and place in a dark area. Check it every few days for moisture and sprout. When you see the sprout. Sink it! Other Nymphaeas can be reproduced by the previous method.
Good luck and let me know how you make out!