Generally speaking, you cannot repair a composite. You replace it.
In certain cases the broken piece can be cut off and 'part mould' repair piece can be joined to it with a similar laminating material. This is often used in repair of grp cars etc. However this would be dubious for any load-bearing structure.
If the composite is carbon based then there are less possibilities as the layup and moulding process could require vacuum, heat and pressure. So there would be no way to ensure a compatible join.
Also when composites are deformed to the point of failure there can be considerable energy stored within the structure. Stress cracks etc may continue to appear for days/weeks afterwards.