พอดีจะบินกลับไปเยี่ยมบ้านเดือนนึงแล้วกลับมาเรียนต่อ  
You can't claim for a VAT refund if you intend to come back to Germany to continue your studies.


https://www.vatfree.com/en/for-travelers
Also for international students

If you are an international student and staying in the EU for six months or less, you are also eligible for a VAT refund.

If you are staying in the EU for a period of six months or more, and you are planning to leave the European Union anytime soon, make sure to deregister from city hall. You will then receive a confirmation of your deregistration which you will need once you visit EU-Customs for a Customs stamp.

You can only reclaim your VAT over purchases made in the last three months before leaving the EU.

How does it work?
https://www.vatfree.com/en/for-travelers#ft-how-does-it-work