It usually means she's going to reapply her makeup so that she looks "fresh" again. A woman might want to do this before she meets with her boyfriend or someone important. That's why women's restrooms at movie theaters and restaurants are always more crowded than men's. ^_^

In that context, it literally means "to get clean" so she is going to take a shower or do something to clean herself. It can also mean "to become presentable", but that would be if she went to a wardrobe.

Thank you everyone and I think I've got it now!Cheers!

Go to the mirror to check the hair, the lipstick, the Mascara, and put on some perfume.

Kat's right