§ 1068 ABGB describes the basic consequence where a repurchase right was granted without further specification. The thing has to be returned in a condition that is not worsened. In return, the purchase price paid is returned. The benefits drawn from the money and from the thing in the meantime are generally set off against each other.
The clause should therefore state how the price is determined and which payments are included. Possession, use, income and the date of return should also be clarified. A flat repayment can create a dispute if the property was used or changed in the meantime.
§ 1069 ABGB addresses improvements and extraordinary preservation costs. If the buyer improved the thing with personal funds or incurred extraordinary costs for its preservation, the buyer is generally entitled to compensation as a bona fide possessor. Liability can arise for culpable changes in value or for frustrating the return.