"It's not that the clubs weren't the right option, I just thought that there is still unfinished business here", he told the official website.
If the club remain in the Championship they can choose to offer Murphy a further year - which enables them to gain a fee if he was to leave in 12 months.
The Irishman saida change of mindset convinced him another year at Glanford Park would be worthwhile.
"Two years ago it seemed to be about going to all these big grounds and experiencing this, and experiencing that, it's not about that this year though" he added.