No need to do it manually, LUNs will trespass to the peer SP when the SP is going down for reboot, and should transfer back to the default when the reboot is completed.  Run a trespass report afterwards or naviseccli -h spaddress trespass mine followed by spbaddress to return all LUNs to their owner.
Hi, I want to reboot one of the SPs in a VNX. Shall I manually tresspass all Luns owned by this one to the surviving SP or it will be done manually? I always try to tresspass them manually but they keep changing back to the other SP I usually have to change the default owner and then change it again. 
LUN Tresspass