That, as it happens, is an unfortunately easy answer to give. "No." He'd been unconscious, unaware, or sedated for most of it, and the one detail he did remember wasn't something that could be easily repeated.

...but that doesn't mean they can't have hope. Even Sans can see that, even now. Especially now, after the night when he'd first transformed. "Another way." Neil will find another way, Sans-Serif and S-4 will help him, Tauriel and Ryoji will make sure he doesn't hurt anyone. Gaster might not be here, but...in a way, he's still better off than he was the last time this happened.