If a judgment is set aside, then the parties are put in exactly the same position as if the judgment was never there. If, using your case, a judgment was given in the second year of a six year limitation period on a contract not under seal, and judgment was set aside 4 years later (i.e. outside of the six year limitation period) then on re-issue of the summons, the defendant would be able to claim that there was no case due to the six years limitation period having been exceeded.(posted 7143 days ago)That having been said, it would be extremely difficult to persuade a judge to set aside a judgment 4 years after it was made, and clearly the judge would be open to suggestion by the claimant that this was a ruse to prevent a "reclaim" because of the limitation act.
A wise judge would perhaps allow the defendant to file a late defence and base the outcome (i.e. leaving the judgment as is, or quashing it) on the subsequent trial.
Two prime factors would be, is there a proper defence which needs to be tried, and secondly, is there a good reason as to why the defendant did not know about the summons and subsequent judgment until 4 years later?