Hi sjbellan,
Yup it is a simple backup and restore.
Or you can just log in by cli and do "show | display set| no-more" on the SRX 240 and copy the config from the screen ( select all copy ) then on the SRX 240H2 do "load terminal set" paste the config on the screen and when you are finished press ctrl+d .
There isn't an SRX 250, maybe you mean SRX 550 ? But it is the same for all series of SRX so no worries.