Ok, thanks. Good to know there's an option.
I don't have the exact link. You can search through www.cpf.gov.sg.
I went with my mom and aunt to CPF to choose their plans. They said it's refundable at death or migration according to the plans chosen, minus whatever annuities already paid out. Only Plan D is non-refundable. Plans A, B and C all are refundable. Choose Plan D only if you're alone without dependants or successors and intend to remain in Singapore till death. At death it's straightforward refund for Plans A, B and C. At migration, a bit more complicated, has to apply and show cause case-by-case. Only on total severence of ties from Singapore, i.e. no more Singapore bank accounts, investments and business interests etc. Otherwise, no lump sum refund, they'd just keep paying your annuities.