This is just another take on solder joint repair. Something I saw today made me think it was time to say it again. :^)
Adding solder is not the same as "reflowing" - if the solder joint is bad, it is likely because not ALL the metal involved was heated above the melting point of the solder. Adding solder to the blob does not make the terminal and the wire hotter; usually the iron itself must conduct heat to the terminal and the wires.
The best repair to a bad solder joint is to remove as much of the old solder as possible - you can get a solder-sucker, or use the woven copper tape with flux which wicks it away. Then, when you can see the metal parts, put the iron onto them for a bit before adding solder. Touch the solder to the terminal and/or the wire, not the soldering iron, so you are sure the metal parts are hot enough. When you see it flow onto the parts, then you can take the iron away. One reason this is best it that the flux inside the solder wire will be in the right proportion. The flux that was with the original solder blob has evaporated already, and the excess solder just dilutes the flux in the added solder.