DRopDown Combox Box vb.NET

After adding data to dropdownlist, you can remove/insert/add a few more into the dropdown. What do you mean by append the data...
if aaa is one of the listitem in dropdownlist, do you mean aaabbb is apending?
If you want to occomplist the same, get the index of aaa in dropdownlist and say dropdownlist.items(index).text="aaabbb".
Hope the above explanation clarifies your query