Something 'appropriate'.

Girls and women are expected to dress a certain way at these kinds of clubs, fortunately her Younger self has plenty of clothes that fit in.
Throwing open the cupboard she first pulls out a thong and slides it on, a simple little black number that will go with anything. She hovers over the barely there skirts. Microskirts are a young girl's game, she's hardly old now, but the style is different to fit her. Instead she moves over to the 'sensible' clothes, things her Younger self only wears when getting dragged somewhere boring. There's a nice pencil skirt she can squeeze into, and once in she grips the hem and rips, tearing a long slit in it that will let anyone know her tiny her thong is. Micro skirts are for girls, hip slits are for women.
Next comes a bra, black, lacy, clasp in the front for easy exposure. Then back to the sensible side of the wardrobe for a white blouse, of which she does all of three buttons up, letting her neckline plunge down to her navel, her bra clasp and breasts basically on full display.
From there it's just a strappy pair of heels that go with the look, and she's done... except for make up. Scurrying over to the vanity she grasps the lipstick her Younger self left behind, deep 'fuck me' red. She presses it to her lips, an indirect kiss with the stupid little siren she watched run out the door.

"I miss Jake," she thought for the millionth time in her life as she looked to the mirror, stealing some eyeshadow as well. "I miss him looking after him, I miss him looking after my stupid little ass." She took a moment to admire herself. If there had ever been a real problem between her and Jake it was the age gap, that was reckless and stupid in itself and she had been lucky she was the one who screwed things up, but the woman she was now... no-one would bat an eye at her hanging off Jake's arm.

"I... I need to catch up."