If you are already receiving a provisional refund you should normally not have to do anything for the following year. The refund should continue automatically. In December you should receive the assessment from the tax authorities confirming the provisional refund for the next year.
Sometimes it happens though that the provisional refund is not automatically continued. This can occur, is our experience, if you bought a property during the year and requested a provisional refund for the first time for part of the year. In this situation it is unsure that the refund for the next year is the same as for the current year.
In the current year you can deduct the costs related to arranging the mortgage, in the next year you can deduct more months of interest. Because of this the tax authorities may not continue the refund automatically. If you don't receive an assessment in December for the next year you should file a new request. From that year onwards the refund should continue automatically.