Night Goblin Warband Question about Trolls

Mar 19, 2018
Melbourne VIC, Australia
Playing around with a Night Goblin list. When it comes to retaining a Troll in the warband, if I don't pay the 15gc per game/sacrifice 2 goblins do I need to re-hire at 200gc for the following games, or can I coax the troll back with 15gc/sacrifice 2 goblins?