Welcome to FT,
bkschlag!
Unfortunately activities such as miles accrual do not extend the validity of M&M miles. You seem to have checked the M&M website already but this is what it says about miles validity.
For how long will my award miles remain valid?
Award miles remain valid for 36 months after the transaction date and then expire – if they have not been used – at the end of that quarter. Miles earned by members who have attained the status of Frequent Traveller, Senator or HON Circle Member or possess a German Lufthansa Miles & More Credit Card* are not subject to mileage expiration.
(*For customers with an international Miles & More Credit Card, special conditions apply.)
We will always inform you two months in advance on your online account statement about any miles which are due to expire at the end of the current quarter.
To help you understand how it works, here is an example. Suppose you flew from Frankfurt to New York on 12 December 2009. The associated miles will expire 36 months after the end of the next quarter, i.e. on 31 December 2012.
If your miles are due to expire at the end of this month, were you notified two months earlier? Since miles expire at the end of a quarter, the earliest they expire must be 31 March 2011. So you should have another month to spend these miles on awards.