Generally, succulent plants like a Jade can be cut back to any extent so it can be cut back to the desired height. Removing the actively growing tips of a branch with cause lower portions of that branch to branch out themselves. Make cuts approximately 1/4" above a node (where a branch is present or where a leaf was).
Put your jade plant in a higher light environment. Reduce the fertilizer application if it has a high phosphorus level. Be patient, with some time your jade plant will be full and happy. They like to be pot bound or nearly so, do not transplant to larger vessel. You can prune it back, but only if it is really leggy.