As mister_rf says, it is good to consult manufacturer's documentation on lifetime and reliability.
From Nichicon info, leakage current doubles every 30 degrees temperature increase for a 200V 470uF 105 degr capacitor. Same document shows that the increase in leakage current is less for a 50V 1000uF device.
A checked an ELNA technical note (on my PC, I don't have the link) and it shows some measurement results for leakage current versus time. The first thousend hours, it drops a bit (think of <50%) and increases during the life time. But after 10000 hours it did not exceed the initial values. All measurements done at the "design" temperature (so 105 degr. for a 105 degr capacitor).
If you can't locate the document I can mail it to you.
It is good to read production related documentation on electrolytic capacitors, as this may affect the service life (solvents may attack the seal).