This is "TAPP12V Connector" and if you google it you will see literally hundreds of sources for them. Here are some examples: one, two, three.
They mostly come pre-wired with slightly more common connector on the other side. You can either use that connector or cut it off and splice the wires.
Main point is - do not waste time looking for pins, buy "Peg Perego battery harness" and use it to replace the connector.
Another option (which I don't like) is to crimp the wire where it is supposed to go - into second pair of tabs. Since you would not be able to crimp insulation too chances are it will break off again eventually.