No, you are not allowed to re-attempt the jump in Rally. HOWEVER, effective 4/4/2012 missing the jump is just an IP (-10) and NOT an automatic NQ. and attempting to re-do the jump shouldn't be an NQ either.
--Regina and the GSDs:
UCDX von Sontausen Holy Grail (The BUNNY!) HGH, UD,RA,BN,GN, ASCA UD RAX High in Trial
PAM Monster Mike SchH2,UDX,OM1,TD,RE,VER
PAM FGDCh Ianna von Sontausen UDX,BH,TD,RE,PT (4.26.1998 - 2.11.2013)