Failure contingencies for Plan Trickster:
1) If it fails early (eg: Illusionist wizard discovering the tricks), fall back immediately to Plan Ambush.
2) If it fails midway (ie: before fatigue/etc sets in), play bait and get 'spotted' in the distance, then run. Swap with an illusory version of you to be seen actually exiting the caves. By the time they chase it outside, they'll realize it was a trick, but they won't know how much of the entire chase was a trick. They'll also know that all of their maps would be useless at that point, and they'd have to start from scratch.
That may be sufficient for them to give up and leave, or they may make another attempt later. If they camp, use harassment tactics to keep them from getting any rest til we eventually run them off. It also gives us time to re-set the traps. If they re-enter immediately, and assuming we have a decent amount of magic left, set off a fireball at ground zero in the middle of them (not directly targetted at any individual) while they try to work through the entrance trap area (passive traps like pitfalls still take care to get around) so they get caught in the AOE (ie: unlikely to directly kill them), then harry until they reach a selected defensive point and re-enact Plan Ambush.
Also, for the Trickster fight, figure that when they encounter the trolls, the trolls will charge them straight on, but one will be held up by the warrior. The second troll should bypass that and continue towards the wizard to prevent the wizard from acting as support fire. The goblins should assist both trolls as convenient, and harry the thief.
By the way, do the goblins have crossbows yet? We should totally put that on our shopping list.