An easy way to do it is to space out the shorter menu items. For example, pad the Text property of your "New" menu item to be "New " so that it has all the extra spaces at the end and that will push over the shortcut.
Update
I suggested automating this in code to help you out. Here's the result of letting the code do the work for you:

I wrote the following code that you can call that will go through all the main menu items under your menu strip and resize all the menu items:
// put in your ctor or OnLoad
// Note: the actual name of your MenuStrip may be different than mine
// go through each of the main menu items
foreach (var item in menuStrip1.Items)
{
if (item is ToolStripMenuItem)
{
ToolStripMenuItem menuItem = (ToolStripMenuItem)item;
ResizeMenuItems(menuItem.DropDownItems);
}
}
And these are the methods that do the work:
private void ResizeMenuItems(ToolStripItemCollection items)
{
// find the menu item that has the longest width
int max = 0;
foreach (var item in items)
{
// only look at menu items and ignore seperators, etc.
if (item is ToolStripMenuItem)
{
ToolStripMenuItem menuItem = (ToolStripMenuItem)item;
// get the size of the menu item text
Size sz = TextRenderer.MeasureText(menuItem.Text, menuItem.Font);
// keep the longest string
max = sz.Width > max ? sz.Width : max;
}
}
// go through the menu items and make them about the same length
foreach (var item in items)
{
if (item is ToolStripMenuItem)
{
ToolStripMenuItem menuItem = (ToolStripMenuItem)item;
menuItem.Text = PadStringToLength(menuItem.Text, menuItem.Font, max);
}
}
}
private string PadStringToLength(string source, Font font, int width)
{
// keep padding the right with spaces until we reach the proper length
string newText = source;
while (TextRenderer.MeasureText(newText, font).Width < width)
{
newText = newText.PadRight(newText.Length + 1);
}
return newText;
}