There is no CGT relief for re-investing.
€55k is too much in one share, so you should sell and take the hit.
If any of your new purchases fall in value, you can sell them before the end of the year and set the loss against the gain.
But maybe there is no hurry to sell. Sell some now. And sell some in the new year to avail of the annual relief. It's small, but you may as well have it.
I did it recently to rebalance my portfolio. It hurts, but it's the right thing to do.
Brendan