All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If you uttered divorce, as this is apparent from your question, then you have divorced your wife as the physical presence of the wife, or her knowledge are not conditions for the divorce to be valid.
In fact, you can divorce her by delegation, phone, writing or any other means of communication. So, if this is the first or the second time you divorced her, then you can take her back if her ‘Iddah (waiting period) has not expired. You do not need a new contract for that, nor a Mahr (bridal money) nor the consent of her Wali, nor even her own consent. But if her Iddah has expired, then you need a fully new marriage contract that requires all the conditions stated above.
On the other hand, if this is the third time you divorced her, then you can no longer marry her unless she marries another man a serious marriage and provided this man has sex with her, then he divorces her or dies. Only then could you marry her after her Iddah from that marriage expires.
If you did not pronounce divorce and you just promised that man that you would divorce your wife in the future, then this is not a divorce; it is only a promise of divorce.
Allah knows best.