Take a cutting from the plant and let it sit on a shelf for 24 hours, then plant it in some potting mix and water it.
You can also take a leaf from the parent plant and stand or lay it on the potting mix. Roots will grow out of the wound.
Try to use a liquid plant fertiliser at 1/4 strength to water them. The low dose fertiliser will provide some nutrients without burning the new developing roots. After a month or so you can use 1/2 strength liquid plant fertiliser. A few months after that go to full strength liquid plant fertiliser.
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Before you take cuttings from any plants, prepare the donor plant. Fertilise the plant every week for a month before taking cuttings. This lets the plant build up some nutrients, which will be stored in the stems and leaves and the cutting can use these nutrients to grow new roots.
Water the plant regularly for a month before taking the cutting. This makes sure the stems and leaves are fully hydrated and the cutting will have more chance of surviving.
If the stem you want to cut has lots of leaves, trim the surplus leaves off a week before you take the cutting. This allows the stem a chance to heal while it is still attached to the plant and the cutting won't need to waste its stored reserves to heal the wounds.