I'm not a sprint expert and certainly don't really have suggestions for you but would be interested in seeing what you do.
Also, it's not 100% clear on what your aim is. IMO there are 3 different phases in a sprint that would require different types of exercises I imagine.
There's explosiveness, top end speed capability and speed endurance. The first 2 probably require some sort form of drills and/or weight routine to see improvements for which I wouldn't be placed to recommend.
On the third, are you looking to maintain your speed over 100 m or longer?
Just some comments to consider and to maybe breakdown the different approaches you might take.
aim is simply to increase anaerobic endurance, so probably just running as fast as possible for as long as possible... I have also found over the years, if I have some sort of sprinting in my training, it's one of the most effective ways of me staying fit... it kicks my metabolism into gear, weight falls off me, all for the sake of 30 mins or so
90-100m is arbitrary simply because it's a distance between two points I know in the field I'm planning to use... obviously if someone has advice on doing long or shorter sprints for better results, I'm all ears...
I also box a bit, so it will aid that 10 fold also
my biggest problem is, over the years I never stuck consistently to a plan....
This year, I made a goal of doing at least 2x 5k runs a week.... I am still on track with this... but I am not seeing the results I expected (much faster 5k, a lot more weight loss etc...)
So just trying to change it up for next year and aim for different fitness goals.... I will still be doing a jog also, but wanted incorporate sprints to see if it made a difference
You've a couple of different goals there. The sprints are good to do for speed no doubt and will improve you until you inevitably plateau without adding anything new.
If your 5 k time has plateaued the new stress could be something as simple as increasing the amount of easy mileage you do.
If your speed has plateaued you could add box jumps, squats or burpees etc. to your week as the new stress. Even 100m sprinting isn't 100% anaerobic workout so improving your aerobic base will improve both your 5k time and contribute a little to maintaining top speed for longer.
For maintaining sprint speed for longer, longer reps but at a lower speed might be a good idea too. I haven't trained for sprinting before so someone might be be able to give a better recommendation. Make sure you give yourself enough recovery between the reps.
On the weight loss, I was amazed to discover how few calories running burns sometimes. What and when you eat matters more.