Centre-back Killock joined Avenue last summer from Evo-Stik League North side Scarborough Athletic.
He started his career at Huddersfield Town, leaving briefly to play in the Northern Premier League for Ossett Albion at the tender age of 15.
The 28-year-old has played the majority of his minutes in a spell at AFC Telford United, where he made 132 appearances.
He went on to spend three years at Harrogate Town, a time which included a short loan stint at Guiseley AFC.
In the 2015/16 campaign he started at Hyde United before joining Scarborough in January, suffering a horrific injury in March as he fractured a number of bones in his face in a match against former club Ossett.