User blog comment:Blub19/When and how did deadpool his regeneration back?/@comment-4651179-20121221223805

Deadpool #63 (final issue):

Deadpool faces ex-FBI agent Allison Kemp's allies T-Ray and Slayback (Gregory Terraerton). After killing them both, Wade convinces Kemp to give up in her attempt to kill Deadpool, who back then accidentally left Kamp quadriplegic during one of her missions.

Suddenly, Evil Deadpool appears, revealed to be alive, and tells Wade that the serum which caused his death was only temporal. That's why Wade's face didn't cure when he got a little bit burned or why a finger he lost in a battle against the Traspter grew again.

After reavealing that the serum didn't work, thus Wade got his healing factor back, Evil Deadpool shoots Wade in the head. End of the issue, but we already know he will regenerate.