‘Recorda Me’ has shifting “Pitch Centres” throughout (Link) and beginning in bar 15 has a set of “Segmented Chains” (Link).
The introduction is in A Dorian, that is, A minor with a raised 6th degree (f#). The song begins the same but shifts the tonal centre to F in bar 15 (Cm – F7 – Bb or II-V-I in B flat. The segmented chain continues in whole steps: from Bb to Ab to Gb to F and back to A dorian. Notice how the melody repeats little rhythmic motifs, giving the piece clear traceable movement.
Preparing for improvisation might include these motifs or new ones. Repetition creates Aural Logic.