To cause form controls such as a text box to be refreshed after updating them before your code goes and does something time consuming and intensive you can use this:
this->Refresh();
This does work, if it doesn't try adding a System::Threading::Thread::Sleep(200) after it.
Feel free to comment if you can add help to this page or point out issues and solutions you have found. I do not provide support on this site, if you need help with a problem head over to stack overflow.