。
The cold bath left him feeling refreshed.
Literal
Cold-water-bath [instrumental-で] he [topic-は] refreshed.
さっぱりする is an idiomatic verb meaning 'to feel refreshed, feel clean, feel clear.' Built from the mimetic さっぱり (clean, crisp, clear) + する. Used for feeling after bathing, eating light food, or having a clear resolution. Here in plain past.