I believe you can save the webpage: https://iancoleman.io/bip39/ as an .html file and move it on a usb drive to the old laptop. then you can use it to enter your 23 words (however you got them-dice, etc) and the webpage will generate the 24th word for you. I don't know if this is as safe for a significant amount of money. I am not technical at all and I have played around with it for fun mostly. There might be a reason not to do this from a security standpoint.