You can change from a fixed rate, but it will cost you. I was told that the penatly for doing this works out the same amount as 6 times your monthy payments or about €9.5K in your case.
It probably wont be worth it, but you can ask your bank for the exact cost and work out what it would save/cost you.
Also, although the ecb rate has fallen and there is talk of another rate cut, this does not mean it will last long, as soon as the ECB sees banks stabilising and the recession in bigger eu countries ending they will put the rate straight back up. So over the remaining 2.5 years the fixed may save you more. I believe the ecb need the rate about 4.5-5 to control inflation (maybe not in the current economy) but these rates will be the norm soon.