You said:
I have heard the argument by OSAS people that you can only be "born again" one time. I'm not sure you can prove this from scripture. "Born again" is a metaphor, comparing our becoming a new creature in Christ to physical birth, however the spiritual birth and physical birth do not compare on all points. For example, after physical birth, a baby can live without its parents, but separated from God we die. A baby has no say in being born, we do regarding being born again.You say you are saved I say I am saved and neither has ever been born again twice.
Regardless of whether we can be born again more than once, God can raise one who has fallen away from the dead. See Ephesians 5:14; "Therefore He says: 'Awake, you who sleep, Arise from the dead, And Christ will give you light'." (NKJV) The context makes it plain that this exhortation is addressed to believers.