Celtic defender Virgil van Dijk insists he never asked to leave the club in the summer, and is happy where he is.
Roberto Martinez is not surprised by the interest shown in James McCarthy but is determined to keep him at Everton.
Seaborne has won three and drawn one of the four matches he has played in since making the temporary move to The Valley.
The 25-year-old was forced to sit out the final match of his original loan spell, last Saturday's 2-2 draw against Brighton.
But Seaborne will get the chance to extend his unbeaten run in the Charlton team after a fresh deal was struck.