Find replace based on data from a separate list

I had tried to post this once before but did a poor job explaining. I am attaching a sample of what I am looking for. To better explain off the sample. When entering text in D2 of "Animal Backround Sorter" tab and press the button it will copy the old and new data to next available cell in L and M columns and then find and replace the values. All of that works well. But lets say later we import the list on the "Imported data" tab. How can I automatically have it make the changes in the L and M columns? Please keep in mind that Land M column continues to grow as more and more animals get changed. Maybe we do not need the L and M columns but from everything I have tried it seems as though I need to keep a running list with all the changes to refer to. I appreciate everything!