Can I achieve +6 diopter with glasses if I am currently +6.5 so that I can get LASIK?

Unfortunately you may not be a candidate for LASIK with the latent Hyperopia of +6.50.  Be patient.

The results of LASIK in farsighted individuals are not as good as those in nearsighted individuals. Nonetheless, LASIK may be effective in reducing your dependance on glasses or contact lenses even at these high levels. Regression and loss of effect are most common in farsighted individuals as you age.   I have observed individuals iwth headaches who are farsighted and sometimes, this can be alleviated by LASIK.  Make sure that you do not have a type of glaucoma in which the angle closes so make sure to seek the care of an eyeMD.

There are other vision correcting procedures including a refractive lens replacement which also would afford you better uncorrect acuity. So, seek a doctor that performs all surgeries and become educated about the pros/cons of each procedure and why the doctor recommends that one for you.

You should shoot your dominant eye +5.50 so you'd be 20/20 at distance now. You should shoot your nondominant eye +7.50 leaving that eye slightly myopic so you'd be able to read without reading glasses both now and for another decade Your MD should test this in contacts for two weeks preop to make sure you like this This is what I would do. 

Depending on the laser your ophthalmologist will use, LASIK is usually only approved up to about +4 to +6 diopters, but the results are much better at 4 diopters or less.  Additionally, farsighted or hyperopic LASIK tends to regress over time, so even if your ophthalmologist considers this procedure for you, it's important to understand that the results will not be permanent and you will either be back in glasses or require periodic enhancements throughout your life.  Hopefully, as our Excimer laser technology advances, extremely farsighted patients like yourself, will see more benefit.

In my Baltimore Maryland practice, I am comfortable treating farsightedness up to 5 or 5.5 diopters, if the corneal shape and thickness will allow it. I use a femtosecond laser to create the flap(Intralase) and a 400 hz Wavelight Allegretto excimer laser, which I think is the best laser platform in the world.  If the prescription goes above this, I will either recommend a lens based procedure(clear lens extraction, refractive lens exchange) or defer the patient for future technology. Outside of the US, there is currently an Intraocular Contact Lens that is available, but it has yet to be FDA approved in the US. If I were you, I would get several opinions and, due to your youth, proceed slowly.