Moore's original deal did not expire until next summer, but 'Well were keen to extend it further despite the 19-year old's cruciate ligament injury in the penultimate match of last season against Inverness Caledonian Thistle.
Surgery has gone well and the hope now is that the striker will be back to play some part next season.
Moore told the club's website: "The club have been excellent and have shown a great deal of faith in me that I will repay.
"Obviously the injury was a huge blow as I wanted to have a good pre-season and really challenge for a starting slot next season.
"However, I couldn't be in better hands with JP (John Porteous) and Adam Stokes in terms of my rehab and, so far, things have being going well.
"Obviously, it wouldn't be right to put a time frame on my return, but I am certainly hopeful it will be ahead of the normal schedule."
Boss Stuart McCall said: "We were delighted with Craig's contribution last season, he really has made the step up.
"He has already proven with his scoring proficiency with the Under 20s, his fruitful time out on loan and his appearances with the first-team, that he is going to have something to offer.
"He's a little different to what we have currently in terms of his style and the way he plays. Obviously his injury is a blow, but this club has a great record of looking after players, nursing them back to fitness and getting the best from them."