Not sure why you would transpose the lick if you are not changing key. I'm assuming what you mean is that you want to vary the lick to avoid too much repetition. Without knowing exactly what the lick is, I'd offer these suggestions:
1. Play the same notes, but change the rhythm (I'll often just set up a root, 5th, b7th, and octave and play it 10 different ways)
2. Shuffle the order of the notes. Instead of G G B G D E G, try G D B G G(octave) E D.
3. Add chromatic passing notes to the primary riff.
4. Play the riff backwards
5. Don't play anything (e.g., Good Times Bad Times)
6. Alternate notes of the riff w/ your guitarist/keyboard player.
Tuning a mellotron doesn't. - Robert Fripp