Well, if there are only couple of dashboards, then you can just create new dashboard in your PROD enviornment using the dashboard xml (Open Dashboard, Edit -> Edit Source XML). After that setup appropriate sharing permissions.
Other option would be to Login to Test environment search head (putty in case of NIX server), copy the dashboard xml from path $SPLUNKHOME/etc/apps/YourAppNameHere/local/data/ui/views and place it in the same path or appropriate path on Production server. Also, copy the corresponding metadata entry from $SPLUNKHOME/etc/apps/YourAppNameHere/metadata/local.meta to corresponding meta file in PROD.
Depending on how many dashboards you have, I would just copy the sourcecode from your test environment and put them in your prod environment.
Go into your prod environment, create the dashboard with the same name, edit the sourcecode button, paste your sourcecode and save..
Did you enrich your data in the test environment? If so then you will need to add these knowledge objects or fields into your prod environment before moving the dashboards
All dashboards should be in a custom app created by you. When you set your permissions from
app, the XML file is copied from your user directory in to the app directory. You can then copy the app directory manually or you can use the App Exporter App: