NimbostratusCache can be done in many places. For example it may be cached on the client, in which case the client's browser cache needs to be cleared. Cache control headers (which you could set on your web server or via an irule) can tell browser's not cache objects on the clientside, but browsers do not have to obey these headers (though most do).
On the other hand, if you have a web acceleration profile on the vip, the objects may be cached on the F5. There are somoe solutions on clearing wa cache and ram cache:
https://support.f5.com/kb/en-us/solutions/public/7000/600/sol7618.html
https://support.f5.com/kb/en-us/solutions/public/13000/200/sol13255.html
https://support.f5.com/kb/en-us/solutions/public/10000/200/sol10200.html
Nimbostratus