Just had a look at some of the Jewel itineraries and it is difficult to tell, my guess is that it does go through the locks on the Caribbean side and up into Lake Gaton and one would assume back down again. It does look like there is an excursion to Old Panama City but I do not think that you will get a cruise through to the far end and back and almost certainly not through the more impressive, iconic Pacific end locks. If you don't get a specific answer it is worth dropping RCI a line or email or ringing them. Sorry, .... Neil.
It goes through two locks into the lake. then comes back again.