Sky Sports understands that Dinamo Zagreb striker Duje Cop is attracting interest from clubs across Europe.
Blackpool boss Jose Riga has admitted his squad is lacking experience as he continues to search for reinforcements.
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.