Task Server provides a task to update specific filter memberships; however, it doesn't provide one to update specifc target memberships.
As policies are assigned to targets in 7.x (can be a combination of filters, lists and groups), it is far easier to update a target than to update the filters and groups that are associated with them.
The following process allows you to correctly identify the target you want to update outside of the resource membership update schedules:
1. Load policy with the Apply To View set to Targets.
2. Run the following query in order to obtain the Guid of that resource target:
--/ Resource Targets
SELECT t.Guid AS TargetGuid,i.Name AS Target,i.Description FROM Item i
JOIN ResourceTarget t ON i.Guid = t.Guid
--WHERE i.Name LIKE '%(portal internal target)' --only portal targets
ORDER BY i.Name ASC
3. Run the following query in order to obtain your required computer list (If duplicate names were returned in the first query, you will need to try them all in order to obtain the results from the policy target that you are looking at):
--/ Targeted computers
SELECT i.Name AS Computer,i.[Last Logon user]
FROM Inv_AeX_AC_Identification i
JOIN ResourceTargetMembershipCache c ON i._ResourceGuid = c.ResourceGuid
WHERE c.ResourceTargetGuid = 'target guid goes here'
4. Utilise the following query in a "Run SQL Query on Server" task
--/ Update resource target
exec spResourceTargetDeltaUpdate @resourceTargetGuid='target guid goes here', @flush=1