Sorry, but, It looks like you need a new, taller box.......you could top, but then I would start new moms asap, and maybe lst them to keep them shorter. Maybe get a "More Indica" strain, most Indicas are shorter in stature.
suppercrop them. do a quick search. ther are plenty of threads that explain the process. you basically pinch the stem, move your fingers 90 degrees and pinch again.