If you cut back leaves it lessens the ability to produce food (photosynthesis). That seems to me to be a detriment toward the plant having the energy needed to produce another crop of flowers. Rebloomers also benefit from another dose of fertilizer soon.

However in zone 5 there is a good chance cold temps. will prevent reblooming. Depends on the cultivar.

If you do a search on rebloom there may be some posts from people in zone 5.

I remove outer leaves that turn brown and die. I don't bother snipping off brown tips.