Aglet Sneaker Shine (ASS) is available in the Shop anytime you need to give those near dead kicks a bit of detailing.

Just look at the tier level of the kicks you need to repair, then have a look at how many repairs they have left, then jump into the shop and decide how much Repair Power you need.

Next minute... boom! There's new life in those old shoes.

(Note that you need to use GA ASS to repair GA shoes)