You can reset the “null” which is level with every leveling system I have had. Seem the most common with Jayco is the Equalizer levelers and if yours are Equalizer her is how to reset it. I have reset ours several times and it does a pretty good job but I always have to tweak it a little manually after the slides are out. I just installed a Levelmate Pro module on our Seneca and love it, makes it easy to get it perfectly level.
Brian & Jeannie
2018.5 Seneca 37RB with tons of mods
2015 Jeep JKU Rubicon
I agree with doing it manually. Auto Level tends to over extend and cause a lot of unnecessary movement. I use the free app from Equalizer on my iPhone to control the leveling system manually. That way I can use the app go outside and plant all four jacks on the ground. Then go inside and level the coach while watching a level. I think it is faster and uses a lot less movement and jerking the coach around.