my zebra plant is growing palm tree like. it has been doing this for a while, every now and then it keeps dropping leaves. the stem is quite long and the leaves that are left on top are beautiful. every now and then i notice that leaves are trying to grow back out of the spots that had already dropped then. they only come out a little and then die. is there anything maybe i could use to get these leaves to grow back out of their original spots? maybe something i could rub on the stem? your help will be greatly appreciated.