Getting the best short field performance out of your Cherokee begins before reaching the end of the runway. This requires leaning to slightly rich of max. power at your runup. This is achieved by leaning to maximum static RPM and then richening the mixture slightly as you would at your cruise altitude. (If you plan to cruise more than 2000 AGL, you will need to further richen the mixture.)
Never stop on the end of the runway. After you are cleared for takeoff, make a rolling turn onto the runway-no flaps. When you reach an angle of 45 deg. to the runway, start accelerating so that by the time you have completed your turn, you are at full throttle. Accelerate to your predetermined rotation speed (this is between 45 and 60 mph depending on mods, temperature and loading), at this speed, pull in 2 notches of flaps, count 1.... 2 and rotate! You can take your first notch of flaps off fairly soon after gaining some speed and take the second one out as you continue to gain speed.
This procedure is like adding 300ft+ to the runway which reduces your "pucker factor" for clearing obstacles. Practice on a longer than needed runway and get comfortable with it before doing it on a short field. I use this procedure on all takeoffs regardless of runway length, as I go into short grass strips regularly and want the procedure to be second nature. By using ths procedure, you will quickly discover that your Cherokee is capable of more than you realized.
For a first-hand account of how well this works, read Jim Cavanaugh's article from Pipers Magazine.