'gǎi tiān zài yuē' kěnéng shì zhēn xiǎng yǐhòu jiàn, yě kěnéng zhǐ shì lǐmào shōuwěi

“改天再约”可能是真想以后见，也可能只是礼貌收尾。

'Let's meet another day' could be a genuine desire to meet later, or just a polite way to end the conversation.