After completing the main pool party, the UPD adds a mode. You keep all tokens and clothing unlocks. New dialogue options appear, including a "Remember when…" feature that references your previous playthrough choices.
Now go dry off, charge your controller, and dive back in. The girls are waiting by the deep end.
You will likely need to buy specific attire for the party. If you've applied for the "modelling" job in-game, remember to wear your bikini under your regular clothes to trigger bonus scenes. Social Multipliers: