If it is the normal membership fee to your A-kasse, then it is not possible to get the paid membership-fees back.
A-kasse can be compared to other kind of insurances.
You pay some money to be insured against something - even if you dont need to use the insurance.
It is the same way with A-kasse/Unemployment Insurance.
You pay for being insured against unemployment, and you can not get money back.