I suggest that you do this at least three or four times in training before you taper for your race (two weeks prior to race day).
To progress to a long run of two or more hours, increase your current long run by 10 to 15 minutes one week and then drop back five minutes the next week. For example, your schedule of long runs may look like this:
... and so forth.
If you're willing to train harder, do two speed workouts each week: repeats and threshold runs. For repeats, begin with three repetitions of three minutes each at 5K effort, with two minutes of jogging between. Add one repetition each week for two weeks; every third week, drop one repeat to allow for recovery.
Here's an example: week one, 2 x 3:00 at 5K pace; week two, 3 x 3:00; week three, 4 x 3:00; week four, 3 x 3:00; week five, 4 x 3:00; and so on. When you reach eight to 10 repeats, stop adding and simply maintain this workout.
Threshold workouts include runs of five to 35 minutes at a pace just a bit slower than your 10K race pace. As with repeats, jog two minutes between efforts for recovery (if you feel you're not able to recover in two minutes, the efforts were too hard).
The progression of these workouts should follow this pattern: two or three weeks running threshold pace for the same total duration before increasing the duration by 10 to 20 percent.
... and so on.
Continue increasing the threshold runs until you reach 30 to 35 minutes of total running time at that pace.
After your race, plan two to three weeks of easy running.