Tony Pulis plans to strengthen Crystal Palace's squad and backroom staff in a bid to help the Eagles stay up.
Celtic boss Neil Lennon has refused to name his transfer targets but confirmed he is looking to strengthen his team.
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.