Giving a Cat Injections?

We have a 12 year old cat who was diagnosed with CRF (chronic renal failure) and need to give her subcutaneous Ringers Lactate 150 cc twice weekly.

She hates them and we have to first catch her, then "trap" her in a towel to give these injections. We were told this will get easier, but the injection times seem to be getting worse, often times ending with little fluid able to be given, if at all. Any suggestions to make these life saving injections easier for her and us would be much appreciated. We are already using Terumo 18G needles, warming the fluid before injection, offering treats during injections and not much is working.