Dim wb As C1XLBook = New C1XLBook
wb.Load(・・・)

Dim xb As C1XLBook = New C1XLBook
Dim source As XLSheet = wb.Sheets(0)
Dim dest As XLSheet = xb.Sheets(0)

Dim row As Integer, col As Integer
For row = 0 To source.Rows.Count - 1
　　For col = 0 To source.Columns.Count - 1
　　　　dest(row, col).Value = source(row, col).Value
　　　　dest(row, col).Style = source(row, col).Style
　　Next col
Next row

xb.Save(・・・)

C1XLBook wb = new C1XLBook();
wb.Load(・・・);

C1XLBook xb = new C1XLBook();
XLSheet source = wb.Sheets[0];
XLSheet dest = xb.Sheets[0];

for (int row = 0; row <= source.Rows.Count - 1; row++)
{
　　for (int col = 0; col <= source.Columns.Count - 1; col++)
　　{
　　　　dest[row, col].Value = source[row, col].Value;
　　　　dest[row, col].Style = source[row, col].Style;
　　}
}

xb.Save(・・・);