a "re-usable" feature is planned to be introduced into SRM, but currently on your version is not available.
As the Cart ID is saved to the SRM:Request form, you could create your own workflow to "duplicate" the Cart contents to a another Cart record for submission. This however is a customisation and would require some design to achieve.
Thanks for your reply..Can you please suggest how to achieve this ? Because I have seen that whenever SR is added to cart it gives the REQ number ,So how can we save a favourite cart and use it multiple times if cart requires REQ IDs to be created for each of the SR which is added to it?