When you introduce a time travel plot where the MC meets their past self, there's an inherent promise in the premise that they'll do SOMETHING with their past self. But so far, all the MC has done is ignore her past self.
I want to clarify that immediately after realizing she time travelled, she beelined for her sempai and the chapter ends with her stating her goal. No mention of past self nor any desire to interact with past self. Clearly selfish in her desire to just want to date and fuck sempai.
It's just the MC never explicitly explained why she's ignoring her past self. She doesn't really reflect on what meeting her past self means.
This did happen in chapter 3 when she was worried meeting her past self would make her disappear.