Okay, let's walk through this step by step.
You are insisting that the gift of forgiveness is not included in the gifts that Paul says are irrevocable in Romans 11:29 NASB. You say that because you say forgiveness is not a gift from God because the Bible does not call it a gift or describe it as gift. But I've shown you where the Bible does describe it as a gift, equating forgiveness of sins exactly with the gift of redemption:
"redemption, the forgiveness of sins" (Colossians 1:14 NASB)
"24 being justified as a gift by His grace through the redemption (the forgiveness of sins--see above) which is in Christ Jesus" (Romans 3:24 NASB)
If you disagree that your forgiveness--your redemption--is not a gift, what did you do to earn your redemption?
So, your doctrine has two choices here:
1) Either acknowledge that forgiveness is a free unmerited gift from God, or
2) say that forgiveness is earned by the one forgiven.
If you say it is earned, obviously, you deny the very essence of grace salvation, and if you acknowledge that forgiveness really is a gift then you must include it in the gifts listed in Romans 11:29, but you can't do that because that would contradict Jesus' words that forgiveness IS revocable in the kingdom. We'll proceed from whichever of the two you choose.
No it's not, because it's proof that it's impossible to say that by virtue of something being given for free apart from works to earn it you can not lose it, or have it taken away.
The feeble attempt that has been made here is the insistence that forgiveness can not be defined as a free gift. That's ludicrous. But if you want to stick with the argument you have no choice but to say you did something to earn your forgiveness since it's not a free gift given from God.