Pivot Table Help! Refresh removes some fields

[JumboCactuar]

Hi,
i have a pivot table with:
1 field in Rows
+
4 fields in values

when my data is cleared and pivot refreshed, i lose 2 of the 4 value fields.

How can i make sure these never aren't removed?
Appreciate any help

edit: if it helps
the 2 fields that are removed are both SUM of values

 

[JumboCactuar]

when i try to add them with no data i get this

any way around this? dont want to keep re-adding these every time