Vba add 1 to number inside text for column

[Fred_111]

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[TD="colspan: 2"]Hello there,[/TD]
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[TD="colspan: 2"]I have a worksheet where I'd like to add 1 year to the Date column and add 1 to a number inside some text in another column.
The Date column, I have sorted, but the number inside text is the worry.
My Col "K" has entries like '12/09/2019' & '17/10/2019'.
Col "L" has 'Birthday, 74 yrs' & 'Wedding Anniversary, 58 yrs'
I can Evaluate the formula into 'new' cells, but how can I update into the existing cells?
My code so far is..

Sub Test_VBA_2()
Dim LastRow As Long
Dim i As Long
With ActiveSheet
    LastRow = Range("J" & Rows.Count).End(xlUp).Row
    For i = 4 To LastRow
    
        If Range("K" & i) <> "" Then
        .Range("K" & i).Value = DateAdd("yyyy", 1, .Range("K" & i).Value)
'''     I'm trying to do a similar thing for Col "L", add 1 to the number inside text.
'''     The formula would be like '=IF(L4<>"",LEFT(L4,(FIND(",",L4)+1))&LEFT(MID(L4,FIND(",",L4)+2,256),2)+1&RIGHT(L4,4),"")
'''     I converted the formula to
'''     .Range("L" & i).Formula = "=IF(.Range(" & Chr(34) & "L" & Chr(34) & " & i)<>" & Chr(34) & Chr(34) & ",LEFT(.Range(" & Chr(34) & "L" & Chr(34) & " & i),(FIND(" & Chr(34) & "," & Chr(34) & ",.Range(" & Chr(34) & "L" & Chr(34) & " & i))+1))&LEFT(MID(.Range(" & Chr(34) & "L" & Chr(34) & " & i),FIND(" & Chr(34) & "," & Chr(34) & ",.Range(" & Chr(34) & "L" & Chr(34) & " & i))+2,256),2)+1&RIGHT(.Range(" & Chr(34) & "L" & Chr(34) & " & i),4)," & Chr(34) & Chr(34) & ")"
'''     Calculate
'''     .value = .value
'''     But it produces a Run-time error '1004'   Application-defined or Object-defined error
        End If
    Next i
End With
'With [M4:M5]    This gives the correct answer but in NEW cells
'  [M4].Value = "=IF(L4<>" & Chr(34) & Chr(34) & ",LEFT(L4,(FIND(" & Chr(34) & "," & Chr(34) & ",L4)+1))&LEFT(MID(L4,FIND(" & Chr(34) & "," & Chr(34) & ",L4)+2,256),2)+1&RIGHT(L4,4)," & Chr(34) & Chr(34) & ")"
'  [M5].Value = "=IF(L5<>" & Chr(34) & Chr(34) & ",LEFT(L5,(FIND(" & Chr(34) & "," & Chr(34) & ",L5)+1))&LEFT(MID(L5,FIND(" & Chr(34) & "," & Chr(34) & ",L5)+2,256),2)+1&RIGHT(L5,4)," & Chr(34) & Chr(34) & ")"
'    Calculate
'    .Value = .Value
'End With

End Sub

Any help would be appreciated.
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[Fred_111]

Sorry Fluff, I missed posts #8 & #9
Ok, so I'm learning, Yes the End With position does matter, I'll have to choose my words better, I stand corrected.
Yes my earlier posts didn't mention adding 1 to col F based on another col, it was an after thought, I'll have to explain better.

I'll try your code and get back to you, thanks for your patience.

 

[Fred_111]

Yep, a simple offset.
Works like a charm Fluff.

Thank-you for you time and patience, it's very much appreciated.

 

[Fluff]

Glad to help & thanks for the feedback.