How do I rabbit proof an old rabbit proof fence?

Rabbit-proof fences are only rabbit proof when there is no way to get through them. This includes no digging and crawling under the old netting and no sneaking under a gate.

Fixing the gate:

it is often just a matter of putting a treated pine post under the gate or where it closes so no digging will happen. It is also important that the gate is always shut!

Fixing the wire:

This is not so hard. If the wire has bent up a bit so the rabbits can easily dig under it, it can easily be pinned back down. You might think the same thing will happen again but if you use tent pegs or the equivalent to pin down the wire, they actually form a wire barrier under the ground so the rabbits might dig but cannot get in without going lower than the bottom of the pegs - quite deep if you use good pegs.

If there are holes in the wire, or the top is not where it should be and there are things beside the fence that rabbits can climb on to get over the top, you will need to clear away the objects and repair the holes.