The natural plant cycle entails flowers blooming and dying off. You should expect this with your peace lily. If your bracts seems to be dropping at a high rate, though, this could be more than simple growth ebb and flow.
Flowers require a lot more nutrients than foliage, so if your plant gets stressed — ultimately if it's worried it may die — it may try to prolong its life by ditching the flowers. Peace lilies prefer stagnation, so moving or transplanting them could take a readjustment period. Let your plant focus on getting acclimated to its new environment for a few weeks; then it should be okay.
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