Brandon McPherson added 15 points for the Crusaders (13-13, 8-6 Horizon), who have won seven of their last nine games.
Valparaiso led 75-66 with just over three minutes to play, but Illinois-Chicago quickly mounted an 11-4 run to pull within two with just under a minute left. Two free throws by McPherson later put the Crusaders ahead 83-79 with 27 seconds to go.
Kreps then hit a 3 as time expired.
Neither team led by more than nine points in a game that featured 10 ties and nine lead changes.