How can I boost my red blood cell count?

Go for a vacation in the mountains… your red blood count will rise to combat the thinner atmosphere. You might get dizzy for the first day.

You could take an iron supplement or eat iron rich foods such a liver, red meat, dark leafy vegetables.

^^What she said.

Become a vampire. OK, well, then just suck the blood out of livers. Or eat the whole liver.

Try cooking all or most your food in a cast iron skillet, doing so will infuse your food with iron.

Take some iron. Iron supplements should be taken on an empty stomach or with something high in vitamin C like orange juice. Food blocks some of the absorption of most iron supplements. Vitamin C helps absorb iron. Since you usually have good iron levels you could just take a daily of 18mg probably and it will help. If I remember correctly you are a man, and multi-vitamin supplements for men usually have 0–6mg. If your wife (if you have a wife) takes a daily supplement, hers likely has 18mg unless she is over 60. You could just steal some of hers for a few weeks.

Dark green leafy veggies like spinach and other dark greens are high in iron. Raisins have iron. Black beans have some iron.