To revert to old ways; to relapse into old habits or practices.
他之前已经改掉了爱拖延的毛病，但最近在新的项目上又旧态复萌了。
He had previously overcome his habit of procrastination, but recently on the new project, he has relapsed into his old ways.
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To revert to old ways; to relapse into old habits or practices.