If I got your details right you are arriving on LH in first class. Then, given your flight is on time, you even should be able to use the additional time at FRA to take a shower in LH's First class lounge before collecting your luggage and boarding the train. As mentioned before, if you buy a first class ticket for the train, you can also use the DB lounge at the train station directly above the platform. They have nice seats, free coffee/tea/soft drinks, and you can just leave 5-10 minutes before the departure of your train. However, the lounge is of course nothing compared to LH's First class lounges.