What's the total volume you have? You need to concentrate them by a factor of 100 to 1000. So you need at least 100-1000 mL if you want 1 mL at 108-109 spores/mL.

Options:

• Centrifuge and remove liquid as needed
• Filtration through a flat filter like the Isopore (Millipore)* in a filter holder and resuspend the spores in your media/buffer/saline

*Isopore filters have a flat non-fibrous surface. They are used for fluorescence microscopy and cells don't get stuck into the fibers like in the cellulose filters, so the cells, or spores in your case, are quite easy to recover

Thanks for your reply, I need total volume 1omicroliter

for 10 uL you need 1-10 mL of your original suspension aprox. You will probably lose some spores though

you can centrifuge your suspension and remove the supernatant  liquid. for accurate results you can count the spores again.