For the shuttle, technically the deorbit burn could be aborted, but the window to do so was extremely limited.
Once the deorbit burn was started, one of the key parameters monitored by the crew was the current height of perigee "HP" displayed on the maneuver display. This was a number in nautical miles and would have started out roughly equivalent to the height of apogee "HA".
The deorbit burn was not intended to reduce the Orbiter's velocity to
a small value, but rather to change its orbital parameters, so that
its orbit intersected the sensible atmosphere. Specifically, it
significantly lowered the orbital perigee.
(note this screenshot is from a orbital insertion burn so the TGT/CUR HP numbers are backwards from that expected for a deorbit burn)
As the burn progressed the HP got smaller and smaller. Before the burn, the ground would have read up to the crew a key number, "safe HP", which the crew would enter into the Deorbit Burn pads.
As long as the "current HP" was greater than "safe HP" the burn could be aborted. This can be seen in the Deorbit Burn Flight Rules card in the Entry Checklist. POST TIG means after ignition, the few problems serious enough to stop the burn are listed in the right hand column.
Below "safe HP" the vehicle is committed to entry. If the deorbit burn fails for some reason below safe HP, it must be continued by some of the many redundant means available: single Orbital Maneuvering System (OMS) engine completion, crossfeed, Reaction Control System (RCS) completion.
If while perigee is still above SAFE HP a failure occurs that severely
impacts OMS capability, the crew will stop the burn. SAFE HP
guarantees at least 24 hours of orbit time, which MCC can use to
properly retarget the deorbit burn and assess the impacts of the
On the other hand, if the failure occurs below SAFE HP, the crew must
do what they can to complete the deorbit burn, which includes using
the aft and forward RCS and possibly a recovery prebank.
Safe HP was generally around 80 nm if memory serves.
Generic Entry Checklist
Space Shuttle Flight Rules
Shuttle Crew Operations Manual