Revoking a talaaq

If you issued one revocable talaaq (i.e. you used the clear words of talaaq when issuing the divorce), then it is permissible for you to revoke the talaaq and take her back in your nikaah as long as her iddat period remains. The way to revoke the talaaq is that you tell her that you are taking her back in your nikaah or you touch her with lust or you kiss her or you have relations with her.

If you touched your wife with lust or you kissed her after you issued the first divorce, then the talaaq has already been revoked and she is back in your nikaah and her iddat had ended. Hence, it is permissible for you to have relations with her.

If you did not touch her with lust nor did you kiss her, then it is permissible for you to revoke the talaaq through any of these actions as long as her iddat period remains (i.e. her third menstrual period does not end). If you do not revoke the talaq and her iddat ends, then she will come out of your nikaah and it will no longer be permissible for you to revoke the talaaq. Thereafter, if you both wish to reunite, then a new nikaah will have to be performed with a new mahr.

And Allah Ta'ala (الله تعالى) knows best.