Voters keep voting for the PAP because 60% are rational enough to know that the PAP is the only party capable of moving the country forward and guiding it through unchartered waters.
PAP's How to continue conning the people rule #1: Always remember to spread propaganda through the state owned press
PAP's How to continue conning the people rule #2: Gerrymandering or redrawing electorate boundaries is always a good way to continue winning. Maybe having Jurong East as part of Tampines GRC might be pushing it too far, but there is absolutely no problem if the electorates are nearby like parts of Hougang is now part of Aljunied GRC.
PAP's How to continue conning the people rule #3: State owned resources = PAP resources. Utilising PA for PAP grassroots events is entirely acceptable. Even if Palmer is grabbing Laura's peaches, that's fine, just don't let the peasants find out. WP is not PAP, so the community centres are denied to them.
PAP's How to continue conning the people rule #4: Controlling the unions is the key to preventing industrial action and unhappy workers from taking down the government like the French and Russian revolution. Filling the unions with your people will ensure that they not only toe your line, but they will be able to prevent and inform you of any ongoings in the unions even before anything pops up.
PAP's How to continue conning the people rule #5: Destroy the opposition. Always remember that they are our enemies, they deserved to be jailed, as going against the PAP is a crime. If they are squeaky clean, try to assassinate the character of the people around them, utilise state institutions to challenge the integrity.
PAP's How to continue conning the people rule #6: If all else fails, bring in more foreigners, as you give them a pink IC without the need to do NS, they will be beholden to you at least for the next decade or so. Just bring in 200,000 more new citizens, you'll have a new vote bank 200,000 large.