You can get algae wafers to provide a steady diet, and that supplemented with what you're already feeding it. I had a sailfin leopard pleco, and every time I would drop a wafer in she would zero in on it and devour it. It might take a while before it realizes its delicious, but eventually it'll gobble it up!!! Zucchini and cucumbers, as well as other greens are great supplements.
plecos are amazing, good luck!!
2.5 gallon nano Snooki Sparkle
29 gallon community Yoyo, J-Wow, Jessica, Snape, Arnold, Nymeria, 6 Gold Neons (all "Goldie")