Can I take 15mg of mobic (meloxicam) once a day and still take 800mg of ibprophen 2times a day for pain?

Better not to mix. Which med works better for you? Discuss with your doctor to get optimal dose of one med for pain & prevent side effects (stomach irritation, easy bruising). Might also save you money.
Potentially risky. Ginger50: you shouldn't. Both drugs, though mechanistically different (oxicam vs propionic acid) are non-steroidal anti-inflammatories and can diminish the production of mucous in your stomach that protects it from your own stomach acid thereby promoting an ulcer. The combo may also predispose you to bleeding and also stress your kidneys and fluid balance.
Chronic pain meds. Taking any "nonsteroidal antiinflammatory drugs" (nsaids) chronically can be risky due to problems from kidney failure and gastrointestinal bleeding. You should see a pain management specialist.
One or the other. Mobic (meloxicam) and Ibuprofen are designed to do the same thing - decrease inflammation. If you feel the need to take Ibuprofen twice a day in addition to the Mobic (meloxicam) - the Mobic (meloxicam) is not doing the job it is supposed to.The Mobic (meloxicam) is designed to last all day. Make sure you take the nsaids with food to prevent irritation of your stomach.If you need to take NSAID that often, time to see your doc.