Fix it!?!? Heck, no! Why would you fix it? If anything, make MORE things destroyable - like walls, rocks, whatever can stop a shell.
Being able to destroy a replicator adds a whole new dimension, especially if the enemy tries to destroy it when you control it. Why, it might even blow up quite dramatically, leveling an area.
"Commander, we can't take the enemy out - they are replicating too fast!"
"Sarge, take a squad of men and destroy the thing."
"But sir! That's suicide!"
"War is hell, son."
BaBOOOM!