best way would be to relist the asset on some other exchange, pay the dividends that were not paid and then let it trade for a couple of months and buy back the bonds as per contract if you wish. You may also execute the buyback following the last trading data from GLBSE (should be found somewhere on these forums).
In all honesty re-listing sounds like a lot of work for miniscule return.
For perspective; I own around half of the 800 bonds, the next largest holding is one quarter and the majority of the rest are single digit amounts (several, like my itchy trigger fingered friend strello, hold one (1) single bond).
My feeling is that 1MH/s bonds are worth somewhere south of 0.05btc, based on the markets decline towards the end of GLBSE and diminishing returns from mining including the looming ASICpocalypse.
Seeking opinions and evidence of similar bonds trading on the new platforms.
If you don't want to re-list (it's quite easy, you just send the file Nefario sent you to an exchange and they have an import script for that), then follow last GLBSE trading data and execute buyback (without paying backward dividends). If you want to make a buyback at the current prices you'll need to pay the missing dividends first.