A. Since you have done it this long, you should likely continue until you switch her to whole milk once she turns 12 months old.
But you don't usually ever have to warm an infant's formula. It is more a personal preference than anything else. Some infants do just fine drinking formula at room temperature or even when it is a little cool. After all, once you switch to whole milk, you likely won't be warming it up anymore and will offer it right out of the refrigerator.
Since she is used to you warming her formula bottles, she might not appreciate your making the change right now. If she is a very easy going baby, she might not care though and you could probably give it a try if you like. Not having to warm the bottles of formula is more convenient...
And because of the risk of scalding burns, remember to not use a microwave to warm your baby's bottles of formula. A microwave heats things unevenly and can lead to super heated pockets of formula in the bottle which can scald your baby's mouth. Although many parents do use a microwave to heat bottles, then vigorously shake the bottle and test the formula before giving it to their baby, it still isn't a safe practice.
It is better to use a baby bottle warmer or some warmed tap water to warm the bottle.