The lifetime rating is defined as the number of hours (typically 1,500) operating at maximum temperature and voltage before reaching the end of life which is when the capacitance has decreased by 20% or ESR increased by 100%.
If the capacitor is used at lower temperature (or voltage) the lifetime will increase significantly as shown in the chart. The part should be replaced not necessarily when it has been used for 1,500 hours (unless constantly at max temp and voltage) but instead when the capacitance has decreased by 20% or the ESR increased by 100%.
Below is a chart showing the approximate values of lifetime at different temperatures for each model. The lifetimes would be the same for the 35F model as well.