Your endurance is actually pretty good, I think. If you can run 1:48 and 2:30 as a 13 year old, you're a class above most high school sophomores.
Focus on running intervals 400m-700m going through the 300/400m mark at about 1-3 seconds faster than race pace and try to do it without straining yourself until 150. You'll be surprised how much this improves things, and it will work both ways, it will help your endurance over 400-1000m races, but it will also help you with that top speed over 80-150m. As always, running repeats of the former intervals at 85-95% effort once every one or two weeks will help you find that last gear to kick to a PR.
However, if you're going into 8th grade/HS, you shouldn't be doing this over the summer. Run cross country, and bump up your mileage. It may not appeal to you, but come May/June it will pay dividends to your running over any distance event (and 400m hurdles!) and will certainly make you one of the best runners in your age group, at least in your area if not in your state. With these kinds of times I would say you should set a reasonable goal to run around 2:25 indoors (or around 3:10-3:20 for 1000m if that's what they contest in your state) and around 2:18-2:23 outdoors. As always, remember to lift, double, do long runs, and enjoy it first and foremost. Best of luck!