I have a friend who has a Non Imm "O" visa which will expire in April, (Single Entry) question is if she gets a re-entry permit and leave Thailand and goes for a couple days to Cambodia and then returns before visa expires, will Immigration stamp her in for another 90 days or will they only give her until visa expire date on visa?

Thanks

Dan

If single entry it has been used so answer is no. A re-entry would only allow stay until current permitted to stay stamp time. The visa date itself has no bearing on this as it became history when person entered Thailand.