No, elephant populations have not revived as a result of the ban, and this is not a reason to relax or lift the ban, because elephants will always be in danger from poachers. Elephants are very desirable, and they are subject to a great deal of suffering from poachers. They should always be protected by law.
I don't think elephant populations will ever fully recover, but they have improved since the ban of ivory trading. Regardless, the ban should remain in effect. Why give people a chance to endanger these poor animals again? It just doesn't make sense. They should be left to live in peace, and to thrive as nature would have it. Allowing ivory trading would probably just do more damage this time around, possibly to the point of extinction. Times have changed, and people have become much more vicious and greedy. This alone is enough of a reason to keep the ban in effect and as strict as it always has been.