Certified GKH Gardening Expert
Was your plant outside for the summer and you recently brought it in? If so, it may drop some leaves, but should regrow.
Also, the color can fade if the temperature is too low, it isn't getting enough light or needs to be fertilized.
https://www.gardeningknowhow.com/houseplants/ti-plant/growing-hawaiian-ti-plant-indoors.htm
It can be rooted from stem cuttings easily. This article tells how:
https://www.ctahr.hawaii.edu/oc/freepubs/pdf/of-33.pdf
Air layering is possible, but takes longer.
https://www.gardeningknowhow.com/garden-how-to/propagation/layering/air-layering-plants.htm