Hi Alexhowe! Yes, I believe you'll have to pay an upfront fee to retain your VRN about $1300, since you're transferring the number plate to your existing vehicle.

For the fees, there are two separate parts that you need to take note of.

Part 1: To retain your VRN, you will need to pay a fee.

Part 2: To use your retained VRN on another vehicle, you may have to pay a top-up fee or you may receive a partial refund.

Check the link to view the details: https://onemotoring.lta.gov.sg/content/onemotoring/home/selling-deregistering/retain-replace-vrn.html