Chromaticism. Given the type of writing in the first part, it would be very easy to either tonal shift down a half step and work your way down to the other idea. (also can use modal shifts, like mediants or submediants).
In fact on a second listen, I'd say that since you are in Gb major of some sense at the end of the first phrase, immediately shift down to F major and repeat the first phrase, but instead of ending on F major, end on [F B Db Ab] and transition to the second part which will be in Ab major.