Sorry, I’m not sure what you’re referring to.
"Since the treaty was launched, Russia has deployed 111 new nuclear warheads, bringing its total number of deployed warheads to 1,648. That treaty limit is 1,550 warheads - a number that must be reached in 2018."
To comply with the treaty by the specified date they'll retire the old stuff. The wouldn't retire it until it was replaced by upgraded new stuff.