Split it and increment it in a function which returns the new value:
Public Function IncrementNumericPart(ByVal Expression As Variant, Seperator
As String, Optional PartIndex As Long) As String
On Error Resume Next
Dim varPart As Variant
Dim varParts As Variant
If Nz(Expression, "")="" Then Exit Function
varParts = Split(varParts, Seperator)
'Exit if the part doesn't exist.
If (PartIndex < LBound(varParts)) Or (PartIndex > UBound(varParts)) Then Exit Function
'Exit if part isn't a number.
If Not IsNmmeric(varParts(PartIndex)) Then Exit Function
'Increment the specified part.
varParts(PartIndex) = CLng(varParts(PartIndex)) + 1
'Concatonate the parts.
Expression = ""
For Each varPart In varParts
If Not Expression = "" Then Expression = Expression & Seperator
Expression = Expression & varPart
Next varPart
'Return function value.
IncrementNumericPart = Expression
End Function
In this case:
NewNumber = IncrementNumericPart(OldNumber, ".", 2)
You could use this in a query or code.