The unbeaten Czechs joined the Olympic Athletes from Russia as direct qualifiers for Wednesday's quarter-final playoff round, with two more last-eight spots up for grabs in Sunday's later final group-stage games.
Unbeaten Sweden and Finland, which took silver and bronze respectively in 2014, will meet to decide one berth while two-time defending champion Canada plays South Korea.
After a Monday break, eight teams will play knockout matches Tuesday to decide qualifiers for the other four quarter-final berths.
Repik's power-play goal opened the scoring 7:09 into the first period but Thomas Rufenacht answered for the Swiss 7:38 later.
Dominik Kubalik's goal 3:02 into the third period lifted the Czechs back on top.
Repik and Roman Cervenka added empty-net goals in the dying seconds after the Swiss pulled goaltender Jonas Hiller for an extra attacker.