I have just complete a couple of roller coasters that have a higher height set on them and I was wondering is there a way I can raise the height of the coaster without needing to re build it again since I build a lot of custom coasters rather than just buying the stock ones?

You can save your custom designs and load them later. Rebuilding them completely in a different position is the only way of moving them, so it's your only option, if that's what you mean.