I don't have tickled pink but I do have a veronica that is pink. I think mine is 'red fox' but I am not sure. Anyway, mine is not as strong a plant as my blue veronicas, but it has returned for a few years and gotten a little bigger each year.

It could very well be that pink veronicas just aren't as sturdy. Ah well.

It might need to be divided. I find that my veronicas go downhill every three or four years - fewer flowers, smaller plants - and dividing them does the trick. Best time to divide for me is fall or early spring.