You'll find it crazy hard to significantly increase mileage at the pace you are used to running. A combination of speedwork/tempo runs at faster pace and long runs at an easy pace will help you eventually get to higher mileage at a pace faster than the 10:30/mile. The ultimate goal is consistsency, so if you start a long run at a 9:30 pace for a long run but end it at an 11:00 mile (with sloppy form, just to get the miles in) you aren't helping your body adjust to the longer mileage.

My former 10k pace was about 8:40/mile, and I trained for my marathon at about a 10:15/mile pace.