New to TR this year - I’ve just finished a training plan. My event was a 216km road event with 3,500m of climbing which I did on Sunday.
I want to add more training to my year but I have no event and I don’t want to start one from the beginning because I feel I’ve done my base riding for the year and want to see how fast I can get over shorter flatter distances for the rest of the year. What do I do for building a new plan?
Nice work finishing that plan and your road event! 
When athletes finish a plan, we generally recommend taking a break away from the bike and training for 1-2 weeks to rest, recover, and refresh. Training takes a significant physical and mental toll, so taking some time off upon completion of a training plan allows the body and mind to bounce back before the next training cycle.
After a mid-season break, if you want to skip the Base Phase, you can look into following a Build and then Specialty plan. You can check out all of our training plans here. If you want to get faster over shorter, flatter distances, then I think choosing something like Short Power Build or General Build and then the Criterium or Rolling Road Race Specialty Phase would be a solid choice for your goals. You can add those plans directly to your TR Calendar so you can skip the Base Phase.
Hope that helps – feel free to let me know if you have any additional questions!