Complex sentence: For that reason, Niclas returned as a guitarist, planning to stay until they could find a suitable replacement, but on 28 February 2011, the band decided that he would instead become the full-time guitarist himself.
Split into simpler sentences: For that reason, Niclas returned as the guitarist, planning to stay until they could find a suitable replacement. On 28 February 2011, the band decided that he would instead become the full-time guitarist himself.