Planted Tank Guru
Join Date: Feb 2010
Location: Newbury Park, CA
The old growth is going to die, it won't look awful in there forever. If you are seeing new growth you could cut the old stuff down to 1/2" or so, that might make it look better to you.
I wouldn't pull up the clumps and replant now, the new stuff is so tiny you wouldn't be able to replant it and the old stuff may have used up its stored resources on the new stuff so might not resprout as vigorously.