One picture runs through the whole word: a line that already exists, and a second pass along it. Think of footprints in wet sand. The walk has been made; the marks are still there; now someone goes along them again, in the same order, looking as they go. Nothing new is being made. The value is in the second pass — you see what you missed, you find what you dropped, or you make the line clearer than it was. Change what the line is made of and you get every sense: your own footprints, another traveller's route, the traces a person left behind in records, or a pencil line on paper.
From the word’s history
Retrace came into English from French retracer, from Middle French retracier. Read as its parts, it is re- (again) plus trace (to draw along or follow a mark), which is exactly the picture the modern senses share.
「retrace」是從法文 retracer 進入英文的，再往前是中古法文 retracier。拆開來看就是 re-（再一次）加上 trace（沿著痕跡描或走）。這個組合正好就是今天各個意思共用的畫面：痕跡已經在，你再走一次。
Wiktionary entry for retrace (etymology text supplied in this batch's evidence packet, source_ref kaikki:3f6f69a190036ae4:908868308:6952)
登入就可以看每一支怎麼連回核心畫面。