although uncommon, sometimes some amount of spectacle power may develop after LASIK is done. This is called regression, and depending on various factors may be correctable through an 'enhancement' LASIK procedure.
The 2 most important factors to take into account are the amount of spectacle power to be treated, and the remaining corneal thickness.
These are similar to the parameters that are taken into account when LASIK is done the first time. Should the cornea be too thin or the spectacle power to be treated too high, then the doctor would advise you against doing any enhancement. Other factors would also be assessed during the pre-enhancement consult such as eye dryness, but mild dryness is not usually a factor against further surgery.
If you are very keen to have an enhancement, you should book an appointment with a LASIK surgeon and have the full work up, including possibly a discussion about monovision if you are in the presbyopic age group (above 40 years of age).