Of course, India must have changed a lot since Jules Verne wrote his book, but I think that its charm remains.

remains 是动词 remain 的第三人称单数现在时形式。remain 的意思是"保持、依然存在"，表示某种状态或特征的持续不变。在这里指印度的魅力"依然留存"、"保持不变"的意思。