To Hark Back

1. (hunting) Of hounds, to retrace a course in order to pick up a lost scent. 
2. (figuratively, US) To return or revert (to a subject etc.), to allude to, to evoke, to long or pine for (a past event or era). 

Usage notes

The forms harken back and hearken back are also found, and have been used since the 1930s, and the bare form harken has been used since the 1980s, though some authorities frown on these and prefer the traditional form hark back.

The eggcorn harp back (influenced by harp on) is occasionally found, but generally regarded as an error.