Unhappy [Q] how get root back?

i de activated root. in tony p buildt 5 cm10.1 and now its gone out of the cm settings.
how do i get i back!
i re installed rom. without wipe didnt restore SU

.... loved my new LG L9 p760 great and love the desin. (dead.. touchscreen broke still works but phone fell again now lcd broken 26 are the parts but i dont think the phone is worth it... so im back to my LG O2X P990 who is also on it's last days.... usb port is freaky)
love my hp touchpad 32gb best 130 i ever spend. But still cheap tablet with dualcore (dead wont charge any more, usb port is broke its charge like 1% in a hour..) :,-( me sad..