A.T. Robertson Commentary Acts 3:19

"Repent ye therefore, and turn again, that your sins may be blotted out, that so there may come seasons of refreshing from the presence of the Lord;" — Acts 3:19 (ASV)

Repent therefore (μετανοησατε ουν). Peter repeats to this new crowd the command made in Ac 2:38 which see. God's purpose and patience call for instant change of attitude on their part. Their guilt does not shut them out if they will turn.

And turn again (κα επιστρεψατε). Definitely turn to God in conduct as well as in mind.

That your sins may be blotted out (προς το εξαλιφθηνα υμων τας αμαρτιας). Articular infinitive (first aorist passive of εξαλειφω, to wipe out, rub off, erase, smear out, old verb, but in the N.T. only here and Col 2:14) with the accusative of general reference and with προς and the accusative to express purpose.

That so (οπως αν). Final particle with αν and the aorist active subjunctive ελθωσιν (come) and not "when" as the Authorized Version has it. Some editors put this clause in verse 20 (Westcott and Hort, for instance).

Seasons of refreshing (καιρο αναψυξεως). The word αναψυξις (from αναψυχω, to cool again or refresh, 2 Timothy 1:16) is a late word (LXX) and occurs here alone in the N.T. Surely repentance will bring "seasons of refreshing from the presence of the Lord."