You should be able to copy/paste the theme data from your old machine, I think it's located in your user account App Data folder. Not sure how to apply it restorspectively, as it's normally there for the installer to read from when loading. [possibly have to reload SE]
....on my machine it's located in: C:\Users\Sean Cresswell\AppData\Roaming\Unigraphics Solutions\Solid Edge\Version xxx
Design Manager Streetscape Limited
Solid Edge ST10 [MP0] Classic [x2 seats]
Worked a treat , thanks.
I copied my custom theme folder from the path you suggested to the same location on the new laptop.
Then started SE2d and selected my theme from the customise menu. Job done.
No need to reinstall.Awsum