Above advice is sound, I was tempted not to add anything in case it added to confusion but I think this worth saying...
As someone wrote above, if you saved your config before changing anything you could just load the saved config file and all should be well. There can be exceptions to this, though... E.g. Could have a situation where fixing a long term issue highlights other problems - Suppose the engine was running open loop due to problem code(s) due to (say) failed lambda probes. In open loop fuel trims are not applied, so if LPG calibration was wrong the engine could have been running 20% lean on petrol and 20% rich on LPG. The engine might run OKish running 20% lean on petrol or running 20% rich on LPG, in which case switching between fuels wouldn't reveal any further drive-ability problems. But, if you fix the probes and closed loop running resumes, then you run on petrol, the fuel trim needed to correct the 20% lean running on petrol is learned/applied so now the engine runs great on petrol. But then if you switched to LPG the engine would at first get a 40% rich mixture giving poor drive-ability, but eventually the incorrect LPG calibration might steer fuel trims back to -20% and now the engine might run great on LPG, but if you then switch back to petrol it will be 40% lean. I know this reads an unlikely set of circumstances, after all we would expect the LPG system to have been calibrated correctly in the first place and fuel trims on petrol not to be so extreme, but I've seen similar sets of circumstances so often this type of scenario seemed worth a mention. Other issues can be revealed after fixing an underlying issue too, such as worn LPG injectors giving some cylinders a far greater dose of LPG than others. What should be drawn from this is that when you get it running properly on petrol, make sure you check LPG calibration as soon as you run on LPG.
If you didn't save your config file but you only changed reference pressure, changing reference pressure back to what it was should do the same. If however you changed one of a few other things such as type of injectors fitted, that might have changed the map back to the default map figures for the last type of injectors you selected
Simon.