Hindi term (edited): चमकालो आज लालिमा अपने ललाट की

1.) If we talk about the meaning that it conveys, keeping in mind the context going on in this beautiful song, the teacher is giving advise to his students that "Make yourself bright with the splendor of nature" or we can say that "Make yourself bright by absorbing nature around you."

2.) In yet another spiritual context, this line can also mean "Enlighten your soul with the splendor of nature."

Why did I refer to 'Soul'? Because according to Hindu mythology, the soul resides in the mind ('ललाट' i.e.forehead ).

Why did I refer to 'Nature'? Because the context of the song is all about the praise of nature.

But after watching the video, and after reading the plot of the movie it becomes clear that, the lead actor is a teacher who is giving advise to his students. So (1.) will work better.

Lalaat means the lines on our brow/forehead. In the symbolic sense, it would mean our fate or bhagya. Lalima means the red glow or redness.

Hence, the meaning of the source term would get translated into: to enhance the glow of your fate or to brighten one's fate.

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Note added at 1 hr (2018-08-21 17:09:07 GMT)
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In essence, it means to secure your future.

पूरा छंद इस प्रकार से हैं, इसे देखने के बाद यह समझ आता है कि कवि प्रकृति और प्रकृति स्वरूप ईश्वर की कृपा को अपने भीतर उतार लेने का आह्वान कर रहा है...
कुदरत की इस पवित्रता को तुम निहार लो,
इसके गुणों को अपने मन में तुम उतार लो,
चमका लो आज लालिमा अपने ललाट की,
कण-कण से झांकती तुम्हे छवि विराट की,
अपनी तो आँख एक है, उसकी हजार है।