  The majority of searches for radio emission from exoplanets have to date
focused on short period planets, i.e., the so-called hot Jupiter type planets.
However, these planets are likely to be tidally locked to their host stars and
may not generate sufficiently strong magnetic fields to emit electron cyclotron
maser emission at the low frequencies used in observations (typically >150
MHz). In comparison, the large mass-loss rates of evolved stars could enable
exoplanets at larger orbital distances to emit detectable radio emission. Here,
we first show that the large ionized mass-loss rates of certain evolved stars
relative to the solar value could make them detectable with the Low Frequency
Array (LOFAR) at 150 MHz ($\lambda$ = 2 m), provided they have surface magnetic
field strengths >50 G. We then report radio observations of three long period
(>1 au) planets that orbit the evolved stars $\beta$ Gem, $\iota$ Dra, and
$\beta$ UMi using LOFAR at 150 MHz. We do not detect radio emission from any
system but place tight 3$\sigma$ upper limits of 0.98, 0.87, and 0.57 mJy on
the flux density at 150 MHz for $\beta$ Gem, $\iota$ Dra, and $\beta$ UMi,
respectively. Despite our non-detections these stringent upper limits highlight
the potential of LOFAR as a tool to search for exoplanetary radio emission at
meter wavelengths.
