consider cutting the growing tip and rooting that. I don't know if you want to do it untill you have a good root structure and the tip is big enough to survive rooting
however, when you do it you will have a tip growing as fast as the one you have and the other one will produce between one and five sprites. These will grow in an aggregate speed (more or less) and when they are big enough you can root them.
in a year or two you could be growing six plants, each doing over a foot a year.