$_ = "INSERT INTO TABLENAME VALUES ('bunch o'f text','another text','anot'cool'her text')";

s/\G
(?<=')
	((?:
		  (?> [^\\']* )
		| \\.
                | '(?![,)])
	)*)
('[,)])
/fix("$1").$2/egx;


print;

sub fix {
	$_[0]=~s~(?<!\\)'~\\'~g;$_[0]
}

##</code><code>##

INSERT INTO TABLENAME VALUES ('bunch o',f text','another text')

##</code><code>##

INSERT INTO TABLENAME VALUES ('bunch o')f text','another text')