Kavya,
The reticulocyte count is a measure of the percentage of young red blood cells, which are produced in the bone marrow and enter the circulating blood. It's actually misnamed, since it's a percentage, not a "count".
There are two reasons the reticulocyte count can rise, one good and one bad:
Good reason: There are more young red blood cells being produced in the marrow.
Bad reason: There are fewer mature red blood cells circulating, because young cells aren't maturing or mature cells aren't surviving.
To tell the difference, doctors may compute a patient's "reticulocyte index" or "reticulocyte production index" (RPI). They can be more useful measures for patients with aplastic anemia.
However, all of these numbers can all be thrown off by a blood transfusion, because the cells they measure aren't all produced by your daughter's own system. Therefore, reticulocyte count measurements may give no useful information when it's soon after a transfusion.
You'd probably get more information from knowing your daughter's reticulocyte count, reticulocyte index, and/or RPI on a series of CBCs when she has had no blood transfusions in between.
The increase you observed in her reticulocyte count may be because her marrow is now functioning better. I hope so. But you'll need to see ongoing test results to find out with more certainty and really see the pattern.