Is it a condition to be secluded with the divorced wife after taking her back and before the expiration of her waiting period if the husband is in one country and the wife is in another?

The

revocation of a revocable divorce (Raji'i divorce) by the husband does not depend on his being alone with her; rather, a verbal declaration indicating revocation is sufficient, such as the husband saying: "I have taken her back" or "I have returned her to my wedlock." It is preferable to have witnesses to the revocation to avoid disputes.