Relaunch Input Box - vba

Question

I have an excel sheet than when its first opened it asks the user to enter a date into the input box and it places it into a cell in the sheet. I have an error handle to pop up an invalid date error box if someone puts in the wrong date. But what I want to do is when an invalid date is entered the original input box for the date pops up again so they can reenter again. I have the code below of what I have written so far but I keep getting an error.
Thanks
ReShowInputBox: cellvalue = Application.InputBox("Please Enter The Date for Data Extracted (dd/mm/yyyy)")
On Error GoTo ErrHandle
ErrHandle:
MsgBox ("Invalid Date")
ReShowInputBox: cellvalue = Application.InputBox("Please Enter The Date for Data Extracted (dd/mm/yyyy)")
If cellvalue = "" Then Exit Sub
ws.Select
ws.Range("A1").Value = DateValue(cellvalue)
MsgBox ("Date Entered!")

Answer 1

How about a simple Do Until Loop:
Dim cellvalue As Variant
Do
cellvalue = Application.InputBox("Please Enter The Date for Data Extracted (dd/mm/yyyy)")
Loop Until IsDate(cellvalue) And IsNumeric(Right(cellvalue, 4)) And IsNumeric(Left(cellvalue, 2)) And IsNumeric(Mid(cellvalue, 4,2))
ws.Range("A1").Value = cellvalue
MsgBox ("Date Entered!")
I tested this pretty thoroughly and it only accepted dates in the exact format you desire.

Answer 2

Here is a simple way to repeatedly ask for a date until you get one, but allow the user to cancel out:
Sub fhskjfs()
Dim i As String, d As Date
i = ""
While Not IsDate(i)
i = Application.InputBox(Prompt:="Enter a date", Type:=2)
If i = False Then Exit Sub
If IsDate(i) Then d = CDate(i)
Wend
End Sub
EDIT#1:
Here is a way to implement a simple format check:
Public Function CheckFormat(i As String) As String
CheckFormat = "junk"
ary = Split(i, "/")
If UBound(ary) <> 2 Then Exit Function
If CLng(ary(2)) < 1900 Or CLng(ary(2)) > 9999 Then Exit Function
If CLng(ary(1)) > 12 Then Exit Function
If CLng(ary(0)) > 31 Then Exit Function
CheckFormat = i
End Function
Sub GetDate()
Dim i As String, d As Date
i = ""
While Not IsDate(i)
i = Application.InputBox(Prompt:="Enter a date", Type:=2)
If i = "False" Then Exit Sub
i = CheckFormat(i)
If IsDate(i) Then d = CDate(i)
Wend
End Sub