'patch up' means to make a simple repair, usually by putting something on the surface. 'her' possibly refers to a boat, as it is unlikely to refer to a woman or girl, and one thing we use the female pronoun for is a boat. So - my guess is that it means a boat has a small hole in it, and they have people who can repair it by (perhaps) putting some fibreglass over the surface. You can 'patch up' a hole in a wall by plastering and painting. You can similarly patch up a small dent in a car.

What Gary said above is true, but I think here it could also be used in the context of a person. In this context, it usually means to apply treatments for non-serious injuries. Like if you clean a wound, put on a band-aid, or get a few stitches. Ex: She got hit by a car, but it was not too serious. When the ambulance arrived, the medics patched up her hand and sent her home.