Use the and
filter:
//rf = RowFilter.regexFilter(filterText.getText(), 0);
List<RowFilter<Object,Object>> filters = new ArrayList<RowFilter<Object,Object>>(2);
filters.add(RowFilter.regexFilter(filterText.getText(), 0));
filters.add(RowFilter.regexFilter(filterText.getText(), 1));
rf = RowFilter.andFilter(filters);
The above code was modified from the example found in Sorting and Filtering.