If your difficult child has a diagnosis of Mood Disorder-not otherwise specified (I have two children with that diagnosis), the treatment is similar to how kids with bipolar disorder are treated: with one or two mood stabilizers plus an atypical antipsychotic. The first-line mood stabilizers are Lithium, Depakote, Lamictal, Trileptal and Tegretol. As MWM pointed out, stimulants like Ritalin and antidepressants like Prozac are big no-no's for kids with mood disorders; they tend to make these kiddos much, much worse. Your difficult child is already on an atypical antipsychotic (Abilify), but it is not enough to offset the bad effects of the Ritalin and Prozac. If you're not working with a board-certified child psychiatrist on the medications, you need to insist on getting that level of care. Only with the right medication mix will you make any progress at all with your difficult child.
Hope you can make some headway with the medications soon.