Hi,
I guess that you are talking about "svc keepalive".
If you are using clientless WebVPN, this is not going to help as this parameter is only for Anyconnect.
If that is the case, I see two things that you could try:
1.) Increase the idle timeout of your group-policy (vpn-idle-timeout )
2.) Smart tunnel the bookmark to your internal Website
If 1 doesn't help, hopefully 2 will.
If you are using Anyconnect, I would take a capture of the traffic between your client and the internal server on the Inside interface of the ASA itself and see what we have there.
Regards,
Nicolas