Montag filed for divorce from Pratt, 27, in July, but after spending time together in Costa Rica – and after Pratt publicly apologized to his wife – Montag, 23, has decided take her hubby back.
"We are back together trying to make things work," the couple tell PEOPLE exclusively. "Costa Rica really put things in perspective. We do love each other and realized we do want to spend the rest of our lives together."
The papers were filled out on Monday by Montag’s attorney, Jodeane Farrell, and officially filed into the court record two days later, according to documents obtained Thursday.
"After spending time together over these past several months Heidi and Spencer have decided to reconcile," Farrell tells PEOPLE.
The couple, who were spotted smooching earlier this month, will return to their status before the court filing, as husband and wife.