The 31-year-old Day, who began his career at Manchester City, has played for numerous clubs including Blackpool, Mansfield Town, Oxford United and most notably Aldershot Town where he captained them to the Conference Premier title in 2007/08.
He came out of retirement to appear in the last three matches for the Tigers after successfully coming through a special training regime with the club.
He has also appeared eleven times for the Wales under-21 side.
Meanwhile, goalkeeper Lawrence Vigouroux has seen his loan extended by Barclays Premier League giants Tottenham Hotspur for a further few weeks until January 24th, which is the maximum allowed for a short loan.
Defender D'Arcy O'Connor has also has his loan extended by Sky Bet League Two side Rochdale for a further month until February 1st.