Hi, did you sort this?
What you need to do is modify the Protection group and change the retention range. If it is a Monthly tape that is set to 11 or 12 months, add 6 months to it i.e. change to 17 or 18 months. If a year tape, change retention to 2 years. As long as the tape has not already been overwritten you will be fine e.g. if you had taken the tape out of circulation. You can also leave the protection group edit until you need the data off the tape. Just read the tape and adjust the retention range to get the data out of expiry (that way you won't have unnecessarily extended the retention range of the whole protection group for 6 months).
If it is Disk storage, the same modification will work, except you will have to change the retention range before it expires. If it already expired (e.g. 2 months ago when you posted), you will be too late now as the disk data will already be overwritten.
Regards
Phil