Dorstener Hildebrandtii – how to handle?

I got this small Dorstenia Hildebrandtii last year in summer. At this time it was about half the height, and aprox nearly as thick. The plant is constantly loosing leafes and growing higher and higher…

The soil is mostly mineralic with about a third part of sukkulent-soil. When I got the plant the soil consisted mostly of organic material with mineralic sand (got it from the local botanical garden).

How do I care for this plant so that it gets a bigger caudex and does not try to reach the sun?