If the trace is still there (just loose) I'd carefully resolder it. Otherwise a bit of thin copper wire is fine.
And try to superglue it back to the PCB as well. (being careful not to get glue where you need to solder the socket again)
If part of the trace is broken off, then cut it where it is solid on the PCB and pull off any remaining loose bit. Use a bit of 30guage wire (aka wire-wrap wire) soldered to the end of the still-solidly-on-the-PCB-trace and the socket pin. I like to leave on the wire insulation in the middle if possible. Note that the average wire stripper tool does not go down to 30 guage, you may have to buy a special tool, but they are not expensive.
I've not used any of those conductive pens so can't say of they are great or poor, no idea.
