Not for sure in Texas but in Oklahoma we just take the plate back to the prorate office and have them switch it to the new truck because you will need a new cab card showing the new unit. Doesn't cost anymore to do it. I am sure Texas is the same.
you have to trun them in and start over they will prorate your refund for the time that they were used . If you supplied signs make sure you get them also and if you supplied the IFTA sticker get it also .