Roy: Why not?
Tyrell: Because by the second day of incubation, any cells that have undergone reversion mutations give rise to revertant colonies like rats leaving a sinking ship. Then the ship sinks.
Roy: What about EMS recombination?
Tyrell: We've already tried it. Ethyl methane sulfanate as an alkalating agent and potent mutagen. It created a virus so lethal the subject was dead before he left the table.
Roy: Then a repressive protein that blocks the operating cells...
Tyrell: Wouldn't obstruct replication, but it does give rise to an error in replication so that the newly formed DNA strand carries the mutation and you've got a virus again. But, uh, this-- all of this is academic. You were made as well as we could make you.
Roy: But not to last.
Tyrell: The light that burns twice as bright burns half as long. And you have burned so very very brightly, Roy.
...
Roy: I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion. I watched C-beams glitter in the darkness at Tan Hauser Gate. All those moments will be lost in time like tears in rain.
Time to die...
Probably not, since most organisms (as opposed to cell cultures) don't die because of the Hayflick limit. If humans were killed by the Hayflick limit, their lifespans would be at least 150 years (according to the latest estimates.)
But in any case, the Hayflick limit is not an absolute constraint: cells can be made to divide forever, blasting the Hayflick limit out of the water.