Good question.
Those previous sins are forgiven and God does not go back on His word.
But everything after apostasy remains for the apostate.
Someone who is apostate is someone who has disconnected from God and, therefore, no longer has eternal life in Christ Jesus which is the only place that a person can find eternal life. (IN Christ Jesus)
Rom 3:21-26
But now the righteousness of God apart from the law is revealed, being witnessed by the Law and the Prophets, even the righteousness of God, through faith in Jesus Christ, to all and on all who believe. For there is no difference; for all have sinned and fall short of the glory of God, being justified freely by His grace through the redemption that is in Christ Jesus, whom God set forth as a propitiation by His blood, through faith, to demonstrate His righteousness, because in His forbearance God had passed over the sins that were previously committed, to demonstrate at the present time His righteousness, that He might be just and the justifier of the one who has faith in Jesus.
Fall from grace; back at square one.