To keep yourself in his thoughts, simply burn an incense or diffuse an oil associated with love - patchouli, rose, ylang ylang, vanilla, etc. - as you meditate over your feelings for him. Focus your intention into the universe by imagining the two of you together in blissful harmony. Picture the special moments you two have shared together, and allow his voice, his appearance, and his personality consume your mind's eye.
This very basic spell should have you coming to the forefront of his mind more often than you would normally. How he chooses to handle this change is in his ball court. He may, overwhelmed with his feelings for you, pursue a relationship ... or, out of fear of future hurt, he may withdraw and become even less receptive. Worse still, if he does intend to carry forward the relationship before it's ready to blossom, he will do so with all his trust issues in tow and unattended to, which forecasts future unhappiness.
That's the trouble with love spells - and toying with people's emotions in general. Everyone handle's them differently, and sometimes they do so in counter-productive ways. You must account for this possibility when you consult magic to solve your problems.
If you're sure he has feelings for you, but hasn't articulated them yet, the best idea is to bide your time and make yourself available to him when he needs you. True love is based on trust and reliability; if you express these virtues to him in indirect ways, he'll come around eventually.
Good luck, and blessed be.